Online Calculators
Professional calculators for finance, health, engineering, and business.
Financial
(97 tools)Loans & Credit
Loan Calculator
Calculate monthly payments, total interest, and amortization schedules.
Deferred Payment Loan Calculator
Free deferred payment loan calculator — see how much interest builds during a payment holiday, whether it capitalises, and what deferring really costs.
Auto Loan Calculator
Calculate car loan payments including sales tax, trade-in, and full amortization.
Loan Amortization Calculator
Generate a full amortization schedule with optional extra payments to pay off early.
Lease vs Buy Calculator
Compare total cost of leasing versus buying a vehicle or asset over the full term.
Credit Card Payoff Calculator
Find how long to pay off your balance and how much interest you will pay.
Boat Loan Calculator
Calculate monthly boat loan payments including sales tax, trade-in, fees, and full amortization.
Down Payment Calculator
Calculate the down payment needed for a home, car, or major purchase, and the resulting loan amount.
Balloon Payment Loan Calculator
Calculate the monthly payment and final balloon payment on a balloon loan, plus total interest and total cost.
Debt Payoff Calculator
Compare snowball vs avalanche strategies across all your debts — time to debt-free and total interest for each.
Student Loan Calculator
Calculate student loan monthly payments and total interest, and see how extra payments shorten your payoff.
Debt Consolidation Calculator
Compare keeping your current debts against a consolidation loan — monthly payment, total interest, and break-even at a glance.
Repayment Calculator
Find the monthly payment for any debt, or how long repayment takes at your current payment — with total interest.
Business Loan Calculator
Calculate business loan payments with origination fees — actual cash received, total cost, and effective APR.
Lease Calculator
Calculate monthly lease payments from price, residual value, term, and rate — with depreciation and finance breakdown.
Mortgage & Home Loans
Mortgage Calculator
Calculate monthly mortgage payments with taxes and insurance, plus a full amortization schedule and extra payment payoff calculator.
Mortgage Refinance Calculator
Calculate monthly savings, break-even month, PMI removal and cash-out impact from refinancing your mortgage.
Mortgage Penalty Calculator
Free mortgage penalty calculator — estimate the cost of breaking your mortgage early, comparing the flat interest charge against the rate differential (IRD).
Mortgage Prepayment Calculator
Free mortgage prepayment calculator — see how much interest and time extra payments save, whether monthly, yearly, or as a single lump sum.
Mortgage Interest Calculator
Free mortgage interest calculator — total interest over the loan, cost per day, and the month your payment finally goes more to principal than interest.
Mortgage Payoff Calculator
Free mortgage payoff calculator — find when your mortgage will be clear, or the monthly payment needed to be debt-free by a chosen date.
Mortgage Points Calculator
Free mortgage points calculator — work out whether buying discount points is worth it, with the break-even month and net saving over your time in the loan.
Everyday Finance
Compound Interest Calculator
See how your investments grow with compound interest.
Savings Calculator
Project your savings over time with regular contributions.
Percentage Calculator
Calculate percentages, percentage change, and percent of a number.
VAT Calculator
Add or remove VAT from any amount.
Salary Calculator
Convert salary between hourly, weekly, monthly, and annual rates.
Interest Calculator
Calculate simple or compound interest, compare compounding frequencies, and see year-by-year growth.
Budget Calculator
Build a monthly budget across needs, wants, and savings, and compare against the 50/30/20 rule.
House Affordability Calculator
Free house affordability calculator — how much home you can afford from your income, debts and down payment using lender 28/36 DTI rules.
Tip Calculator
Calculate the tip, total bill, and per-person split for any service — with quick percentages and a round-up option.
Net Worth Calculator
Add up what you own and subtract what you owe — your net worth, debt-to-asset ratio, and financial health at a glance.
Emergency Fund Calculator
Find your emergency fund target from essential expenses, track progress, and see how long until you are fully funded.
Savings & Retirement
Retirement Savings Calculator
Project your retirement nest egg and estimate monthly income based on savings, contributions, and returns.
Annuity Calculator
Calculate the future value of an annuity from principal, regular contributions, rate, and term — with year-by-year growth and scenario comparison.
Annuity Payout Calculator
Find how much an annuity pays out per period, or how long your savings will last at a given withdrawal rate.
401(k) Retirement Calculator
Project your 401(k) balance at retirement with employer match, salary growth, and returns — plus a 4% rule income estimate.
CD Calculator
Calculate certificate of deposit growth to maturity with any compounding frequency — interest earned and effective APY.
Tax & Accounting
Depreciation Calculator
Calculate asset depreciation using Straight-Line, Double Declining, or Sum-of-Years.
Tax Bracket Calculator
Find your marginal tax rate and federal income tax liability by filing status (US 2024).
Payroll Calculator
Calculate gross-to-net pay with federal withholding, FICA, and state taxes (US).
Sales Tax Calculator
Add or remove sales tax from any amount for US states and international jurisdictions.
Income Tax Calculator
Estimate income tax liability across multiple countries with progressive bracket calculation.
Corporation Tax Calculator
Calculate corporate tax liability for UK, US, Ireland, Germany, and more.
PAYE Calculator
UK PAYE 2024/25 — calculate income tax, NI, pension, and take-home pay.
Withholding Tax Calculator
Calculate tax withheld at source on dividends, interest, royalties, and services.
Rental Income Tax Calculator
Calculate tax on rental income after allowable expenses and depreciation.
Property Tax Calculator
Estimate annual property tax from assessed home value, local mill/tax rate, assessment ratio, and homestead exemptions.
Capital Gains Tax Calculator
Estimate CGT on asset sales for US, UK, Australia, and more.
Betting Tax Calculator
Calculate tax on gambling winnings by jurisdiction. Includes US, UK, Australia, and more.
Turnover Tax Calculator
Simplified turnover-based tax for SMBs (South Africa, Philippines, Rwanda, and custom).
Cryptocurrency Tax Calculator
Calculate crypto capital gains tax using FIFO, LIFO, HIFO, or Average Cost. Covers US, UK, Australia, Canada and more.
Investing & Markets
TVM Calculator
Solve for present value, future value, rate, or periods using Time Value of Money.
NPV Calculator
Determine investment profitability by discounting future cash flows to the present.
IRR Calculator
Calculate the Internal Rate of Return — the expected annual growth rate of an investment.
CAGR Calculator
Compute the Compound Annual Growth Rate of any investment over a specified period.
Bond Yield Calculator
Find yield to maturity or fair price for any bond given coupon rate and term.
Dividend Yield Calculator
Calculate dividend yield, annual income from your shares, and yield on cost from price and per-payment dividends.
Corporate Finance
WACC Calculator
Calculate Weighted Average Cost of Capital from equity, debt, and preferred stock.
Operating Leverage Calculator
Analyze how a sales change impacts operating income using degree of operating leverage.
Business Valuation Calculator
Estimate enterprise value using EBITDA, revenue multiples, or P/E ratio.
Ad Revenue Calculator
Estimate daily, monthly, and annual ad revenue from page views, RPM, and fill rate.
DCF Calculator
Value an investment by discounting projected free cash flows and terminal value.
Asset Impairment Testing Calculator
Run an IAS 36 impairment test — compare carrying amount against recoverable amount (fair value less costs of disposal vs value in use).
Loan Loss Provision & Credit Risk Calculator
Calculate expected credit loss (ECL = EAD × PD × LGD) for a single exposure or an IFRS 9 staged portfolio.
Shipping & Commerce
Shipping Rates Calculator
Estimate shipping costs by package weight, dimensions (dimensional weight), and carrier.
Car Rent Cost Calculator
Calculate total car rental cost including daily rate, insurance, extras, mileage, and fuel.
Commission Calculator
Calculate sales commission using flat rate, tiered brackets, or split between multiple reps.
Insurance & Protection
Payment Fees
Stripe Fee Calculator
Free Stripe fee calculator — work out processing fees, what lands in your account, and what to charge to receive a set amount, including international and currency-conversion add-ons.
Shopify Fee Calculator
Free Shopify fee calculator — plan cost plus transaction fees, the third-party gateway surcharge, and which plan is cheapest at your sales volume.
PayPal Fee Calculator
Calculate PayPal transaction fees and find out how much to charge to receive a specific amount.
Utilities & Bills
Electricity Cost Calculator
Estimate the running cost of any appliance or your whole household from wattage, hours of use, and your electricity rate.
Fuel Cost Calculator
Free gas & fuel trip cost calculator — total fuel cost, litres or gallons used, and cost per mile or km, with round-trip and split options.
Economics
GDP Calculator
Calculate Gross Domestic Product using the Expenditure Method (C + I + G + net exports).
Inflation Calculator
CPI inflation by year (1913–2024) plus forward and backward flat-rate modes — with a value chart.
GDP Per Capita Calculator
Measure economic output per person and compare living standards across countries.
Ratio Analysis
Gross Profit Ratio Calculator
Calculate gross profit ratio (gross margin) from net sales and cost of goods sold, with industry benchmarks.
Operating Ratio Calculator
Calculate the operating ratio — COGS plus operating expenses as a percentage of net sales — to measure operating efficiency.
Quick Ratio (Acid-Test) Calculator
Calculate the quick ratio (acid-test ratio) to measure short-term liquidity without relying on inventory.
Expense Ratio Calculator
Calculate the operating expense ratio — total expenses as a percentage of net sales — with a full cost breakdown.
Operating Profit Ratio Calculator
Calculate the operating profit ratio (operating margin) — operating profit as a percentage of net sales.
Net Profit Ratio Calculator
Calculate the net profit ratio (net margin) with a full income-statement walk from sales down to net profit.
Administrative Expenses Ratio Calculator
Calculate the administrative expenses ratio — admin overhead as a percentage of net sales — to benchmark back-office efficiency.
Debt Service Coverage Ratio (DSCR) Calculator
Calculate the Debt Service Coverage Ratio (DSCR) from net operating income and total debt payments to see if cash flow covers debt obligations.
Inventory Turnover Ratio Calculator
Calculate inventory turnover ratio and days inventory outstanding from COGS and average inventory, with industry benchmarks.
Receivables Turnover Ratio & Average Collection Period Calculator
Calculate accounts receivable turnover and average collection period (days sales outstanding) to measure how fast customers pay.
Payables Turnover Ratio & Average Payment Period Calculator
Calculate accounts payable turnover and average payment period to see how quickly a business pays its suppliers.
Working Capital Turnover Ratio Calculator
Calculate working capital turnover ratio to measure how efficiently a business uses working capital to generate sales.
Fixed Asset Turnover Ratio Calculator
Calculate the fixed asset turnover ratio to measure how efficiently a business uses fixed assets (PP&E) to generate sales.
Absolute Liquid Ratio Calculator
Calculate the absolute liquid ratio (cash ratio) — cash, bank, and marketable securities against current liabilities — the strictest test of short-term liquidity.
Earnings Yield Ratio Calculator
Calculate the earnings yield ratio (EPS ÷ share price) — the inverse of the P/E ratio — to compare stock earnings power against bonds and other assets.
Price Earning (P/E) Ratio Calculator
Calculate the price-to-earnings (P/E) ratio from share price and earnings per share to gauge stock valuation versus peers and the market.
Capital Gearing Ratio Calculator
Calculate the capital gearing ratio — fixed-cost capital (debt + preference shares) against equity shareholders' funds — to assess financial risk and leverage.
Proprietary Ratio Calculator
Calculate the proprietary ratio — shareholders' funds as a share of total assets — to see how much of the business is financed by owners versus creditors.
Debt-to-Equity Ratio Calculator
Calculate the debt-to-equity (D/E) ratio — total debt against shareholders' equity — to measure financial leverage and balance-sheet risk.
Health & Fitness
(40 tools)Core Health Metrics
BMI Calculator
Calculate your Body Mass Index (BMI) and health category.
Body Surface Area Calculator
Free body surface area (BSA) calculator — Mosteller, Du Bois, and Haycock formulas in m² from height and weight.
A1C Calculator
Free A1C calculator — convert between HbA1c percentage and estimated average glucose (eAG) in mg/dL and mmol/L.
BMR Calculator
Calculate your Basal Metabolic Rate and daily calorie needs.
Age Calculator
Calculate exact age in years, months, and days.
Calorie Calculator
Calculate daily calorie needs based on activity level — results in calories (kcal) or kilojoules (kJ).
Ideal Weight Calculator
Find your ideal body weight using multiple formulas.
Water Intake Calculator
Calculate daily water intake recommendations by gender, weight, and activity level.
Body Composition
Body Fat Percentage Calculator
Estimate body fat % using the US Navy circumference method.
Lean Body Mass Calculator
Calculate lean mass and fat mass using three established formulas.
Waist-to-Hip Ratio Calculator
Assess your body shape and cardiovascular risk with WHR.
Waist-to-Height Ratio Calculator
Free waist-to-height ratio (WHtR) calculator — check central-fat health risk with the simple "waist under half your height" rule.
Army Body Fat Calculator
Estimate body fat with the US Army tape test (AR 600-9) and check it against official age-group standards.
Nutrition & Calories
TDEE Calculator
Calculate your Total Daily Energy Expenditure by activity level.
Calorie Deficit / Surplus Calculator
Find your daily calorie target to lose, maintain, or gain weight.
Macro Calculator
Calculate ideal protein, carbs, and fat intake for your goal.
Nutrition Calculator
Calculate your personalised daily nutritional requirements — calories, protein, carbs, fat, fibre, and water.
Protein Calculator
Calculate your daily protein needs by weight, goal, and activity level — with per-meal targets and scenario comparison.
Fat Intake Calculator
Calculate your recommended daily fat intake (20–35% of calories) and saturated fat limit, based on your calorie needs.
Carbohydrate Calculator
Calculate daily carbohydrate needs for standard, low-carb, or keto eating styles, plus sugar limits and fibre targets.
Cardio & Workout
Target Heart Rate Calculator
Find your heart rate zones for fat burn, cardio, and peak training.
Maximum Heart Rate Calculator
Free max heart rate calculator — estimate your maximum heart rate (220−age and Tanaka) and all five training zones.
Calories Burned Calculator
Estimate calories burned for any exercise using MET values — results in calories (kcal) or kilojoules (kJ).
Pace Calculator
Calculate running pace, finish time, or distance with race projections.
VO2 Max Calculator
Estimate your cardiovascular fitness and VO2 max score.
Heart Rate Recovery Calculator
Measure how fast your heart recovers after exercise.
Wilks Calculator
Compare powerlifting strength across bodyweights using Wilks score.
Rest Timer Calculator
Find optimal rest periods between sets with a built-in timer.
One Rep Max (1RM) Calculator
Estimate your one-rep max from any set using Epley, Brzycki, Lombardi, and O'Conner formulas — with training percentages.
Daily Life & Wellness
Sleep Quality Calculator
Find the best bedtime or wake-up time based on 90-min sleep cycles.
Pregnancy Due Date Calculator
Calculate your estimated due date, trimester, and milestones.
Period Calculator
Predict your next 6 periods, fertile windows, and ovulation dates.
Ovulation Tracker
Estimate your fertile window and ovulation day for family planning.
Blood Alcohol (BAC) Calculator
Estimate blood alcohol concentration by weight, gender, and drinks.
Step to Distance Calculator
Convert daily steps into km or miles based on your stride length — with walking time and calorie estimates.
Smoke Cost Calculator
Calculate how much smoking costs you daily, monthly, and yearly — and what you could save by quitting.
Dog & Cat Age Calculator
Convert your dog or cat's age into human years using modern veterinary guidance — with size adjustment and life stage.
Engineering
(50 tools)Simple Machines
Gear Ratio & Torque Calculator
Free gear ratio calculator — output speed, torque and direction across a train of up to five gears, with the gears turning on screen at their real relative speeds.
Lever Calculator
Free lever calculator — mechanical advantage and effort force for class 1, 2 and 3 levers, with an animated beam and fulcrum.
Wheel and Axle Calculator
Free wheel and axle calculator — mechanical advantage and effort for a windlass, winch or capstan, with efficiency and a turning diagram.
Pulley Calculator
Free pulley calculator — mechanical advantage from supporting rope segments for hoists, lifts and block and tackle, with rope length and efficiency.
Inclined Plane Calculator
Free inclined plane calculator — mechanical advantage, ramp angle and the push needed with or without friction, for ramps and ladders.
Screw Calculator
Free screw calculator — mechanical advantage from thread pitch and handle radius for jacks, clamps and vices, with realistic efficiency.
Wedge Calculator
Free wedge calculator — splitting force and mechanical advantage from wedge length and thickness, for axes, chisels and splitting mauls.
Mechanics & Motion
Velocity & Acceleration Calculator
Free kinematics calculator — solve final velocity, acceleration, or displacement with the constant-acceleration equations.
Trajectory & Projectile Motion Calculator
Free projectile motion calculator for horizontal, oblique (angular), and vertical projectiles — range, max height, time of flight, and impact speed with an animated trajectory.
Free Fall Calculator
Free fall calculator — fall time, impact velocity, and speed from any drop height and gravity, with an animated drop.
Kinetic Energy Calculator
Free kinetic and potential energy calculator — KE = ½mv² and PE = mgh in joules, with an animated energy illustration.
Momentum Calculator
Free momentum calculator — p = m·v in kg·m/s, with the kinetic energy alongside so you can see why momentum and energy are different ideas, a stopping force from any stopping time, and a second object to compare against.
Simple Harmonic Motion (SHM) & Pendulum Calculator
Free SHM calculator for a pendulum or a mass on a spring — period, frequency, angular frequency, maximum speed and acceleration, with a live animation beside a synchronised graph of position, velocity and acceleration.
Elastic & Inelastic Collisions Calculator (Momentum)
Solve a one-dimensional collision between two bodies and watch it happen: elastic bounces, perfectly inelastic sticking, and every coefficient of restitution in between, with momentum and kinetic energy side by side.
Impulse Calculator
Free impulse calculator — J = F·Δt = m·Δv, with peak force as well as average, deceleration in g, and an animated impact beside a force–time curve whose shaded area is the impulse.
Force Calculator
Free Newton's second law calculator — F = m·a, with the acceleration in g, the time to 100 km/h, and a block that really accelerates beside a velocity–time line and a same-force-different-mass race.
Torque Calculator
Free torque calculator — τ = F·r·sinθ in N·m, lb·ft, lb·in and kg·cm, with the effective lever arm drawn as a perpendicular you can watch collapse as the angle closes, plus angular acceleration from τ = Iα.
Hooke's Law Calculator
Free Hooke's law calculator — F = k·x with the energy stored shown as the triangle under the force–extension line, plus series and parallel stiffness and the natural frequency when a mass is hung on it.
kg to Newtons Calculator
Free kg to newtons calculator — weight on Earth, the Moon, Mars and nine other bodies, plus apparent weight in an accelerating lift, with the block drawn the same size everywhere so only the arrow changes.
Newton's Third Law Calculator
Free Newton's third law calculator — equal and opposite forces with visibly unequal accelerations, showing why momentum divides equally between a pair and kinetic energy does not.
Electronics & Circuits
Solar Power Calculator
Free solar power calculator — how much energy your panels produce against what your devices consume, with the surplus or shortfall and how many more panels would close it.
RLC Circuit Simulator (Transient Response)
Free RLC circuit simulator — damping ratio, natural frequency, overshoot and settling time for a series RLC step response, with charge flowing round the loop and a live oscilloscope trace.
AC Waveform & Phasor Diagram Calculator
Free AC waveform and phasor calculator — RMS, peak, phase angle, lead and lag, and the power triangle, with a rotating phasor that traces out its own sine wave.
Ohm's Law Calculator
Calculate voltage, current, resistance, and power.
Voltage Divider Calculator
Free voltage divider calculator — output voltage, current, and power dissipation from Vin, R1, and R2.
LED Resistor Calculator
Free LED resistor calculator — exact and standard (E24) resistor values for any LED circuit, with power rating and live circuit diagram.
Resistor Color Code Calculator
Free resistor color code calculator — decode 3, 4, 5, and 6-band resistors to resistance, tolerance, and temp coefficient with a live preview.
Capacitor Calculator
Free capacitor calculator — solve charge, capacitance or voltage from Q = CV, plus the RC time constant, with an animated charging diagram.
Capacitor Energy Calculator
Free capacitor energy calculator — stored energy from ½CV² in joules and millijoules, with the charge-voltage triangle drawn out.
Capacitors in Series Calculator
Free capacitors in series calculator — total capacitance in series or parallel, plus how the supply voltage divides across each part.
Capacitor Size Calculator
Free capacitor size calculator — pick a smoothing or timing capacitor from load current, ripple and frequency, snapped to standard E6 values.
Dipole Calculator
Free dipole calculator — half-wave antenna length from frequency with velocity factor, and electric dipole moment from charge and separation.
Materials & Structures
Reynolds Number & Pipe Flow Calculator
Free Reynolds number calculator — laminar, transitional or turbulent, with friction factor, pressure drop and flow rate, and an animation of the flow pattern changing as you drag the velocity.
Concrete Mixer and Batch Calculator
Free concrete mixer and batch calculator — volume with wastage, M15/M20/custom mix ratios broken down into cement bags, sand and gravel by weight, water from the w/c ratio, and the batch count from your mixer’s usable capacity rather than its drum size.
Concrete Calculator
Calculate concrete volume for slabs, footings, and columns.
Pipe Volume Calculator
Calculate the volume and flow rate of a pipe.
Density Calculator
Free density calculator — solve density, mass, or volume from the other two, with unit conversions and a float-or-sink check.
Waves & Signals
Geometric Optics & Lens Refraction Calculator
Free thin-lens calculator — image distance, magnification, real or virtual, upright or inverted, with a live ray diagram showing the parallel, focal and central rays bending through a convex or concave lens.
Amplitude Calculator
Free amplitude calculator — find amplitude, period, frequency, and phase shift of y = A·sin(Bx + C) + D, with a live animated wave.
Wavelength Calculator
Free wavelength calculator using v = f·λ — solve for wavelength, frequency, or wave speed, with sound and light presets and an animated wave.
Analog to Digital Calculator
Free analog-to-digital calculator — bit depth, quantization levels, sample rate, bit rate, and Nyquist check, with an animated sampling diagram.
Speed of Sound Calculator
Free speed of sound calculator — speed in air by temperature plus water, steel and other media, with Mach number and distance from an echo delay.
Home & Construction
Square Footage Calculator
Free square footage calculator — area of rectangles, circles, triangles and trapezoids in ft², m², yd² and acres, with material cost.
Stair Calculator
Free stair calculator — number of risers, exact riser height, tread depth, total run, stringer length and stair angle from your total rise.
Paint Calculator
Free paint calculator — how much paint to buy for a room from wall dimensions, coats, and coverage, in litres or gallons, with an animated wall.
Tile Calculator
Free tile calculator — number of tiles and boxes needed for any floor or wall area, tile size, and waste allowance.
Flooring Calculator
Free flooring calculator — square footage, boxes, and cost of laminate, hardwood, or vinyl for a room, with a waste allowance.
Mulch & Soil Calculator
Free mulch, soil, and gravel calculator — cubic yards or metres and bags needed for any bed area and depth.
BTU Calculator
Free BTU calculator for AC sizing — cooling power and AC tonnage for a room from area, sun exposure, and occupants.
Roof Pitch Calculator
Free roof pitch calculator — angle, x-in-12 pitch, slope factor, and grade from roof rise and run.
Business
(7 tools)ROI Calculator
Calculate Return on Investment (ROI) percentage.
Profit Margin Calculator
Calculate gross, operating, and net profit margins — plus stock trading margin and currency exchange margin modes.
Break-Even Calculator
Find the break-even point for your business or product.
Payback Period Calculator
Calculate simple and discounted payback periods for any investment — with cash flow growth and time-value warnings.
Discount Calculator
Calculate sale price after discount or find discount percentage.
Markup Calculator
Calculate selling price from cost with desired markup.
Time Card Calculator
Free time card & timesheet calculator — total weekly hours from clock-in/out times minus breaks, with optional hourly pay.
Math & Education
(55 tools)Arithmetic & Algebra
Operation Calculator
Perform quick calculations — add, subtract, multiply, and divide — with all four results at a glance and history.
Factor Calculator
Find all factors, prime factorization, GCF, and LCM of any whole number.
Root Calculator
Calculate square roots, cube roots, nth roots, and simplify radical expressions.
Factorial Calculator
Free factorial calculator — n! with its digit count, plus a log-scale chart of how it outruns exponential and polynomial growth, which is why brute-forcing permutations fails so early.
Exponent Calculator
Calculate powers, negative and fractional exponents, and scientific notation with full step-by-step breakdowns.
Rounding Calculator
Round any number to the nearest whole, tenth, hundredth, ten, hundred, and more — with half-up, banker's rounding, ceiling, floor, and truncate modes.
Percent Error Calculator
Calculate percent error between a measured/estimated value and the actual value, with absolute and signed error.
GPA Calculator
Calculate your semester and cumulative GPA (Grade Point Average) on the 4.0 scale from course grades and credits.
Grade Calculator
Free weighted grade calculator — combine homework, tests, and exams by weight into your overall grade, letter grade, and GPA points.
Final Grade Calculator
Find the score you need on your final exam to reach a target overall grade, based on your current grade and the final's weight.
Fractions Operations Calculator
Add, subtract, multiply, and divide fractions — with simplified results, mixed numbers, decimals, and step-by-step working.
Statistics Calculator
Free statistics calculator — mean, median, mode, range, variance, and standard deviation (sample and population) from any list of numbers.
Standard Deviation Calculator
Free standard deviation calculator — sample and population standard deviation, variance, and mean from any list of numbers, with a histogram.
Average Calculator
Free average calculator — mean, median, mode, range, and sum from any list of numbers, with a distribution histogram.
Ratio Calculator
Free ratio calculator — simplify a ratio to its lowest terms or solve a proportion A:B = C:D for the missing value.
LCM & GCD Calculator
Free LCM and GCD (HCF) calculator — least common multiple and greatest common divisor of two or more whole numbers.
Trigonometry Calculator
Free trigonometry calculator — sin, cos, tan and their reciprocals for any angle, plus a right-triangle solver from two sides.
Probability Calculator
Free probability calculator — single-event probability and combined odds of two independent events (and, or, neither).
Quadratic Equation Solver
Free quadratic equation solver — real and complex roots, discriminant, and vertex of ax² + bx + c = 0, with the formula shown.
Permutations & Combinations Calculator
Free permutation and combination calculator — nPr and nCr with the actual arrangements laid out and grouped by selection, so you can see the r! orderings that collapse into one combination.
Log Calculator
Free logarithm calculator — log to any base, plus natural log (ln), log₁₀, and log₂, with verification and change-of-base.
Numbers & Conversions
Binary ⇄ Decimal Converter
Convert between binary, octal, decimal, and hexadecimal with a place-value breakdown.
Cooking Measurement Converter
Free cooking measurement converter — cups, tablespoons, teaspoons, ml and grams for flour, sugar, butter and more.
Hex to RGB Converter
Free hex to RGB converter — with the colour actually shown, channel bars, HSL, the position on a colour wheel, and the WCAG contrast that decides whether text on it can be read.
Fraction to Decimal Converter
Convert fractions to decimals and decimals back to simplified fractions, step by step.
Decimal to Percent Converter
Convert decimals to percentages and percentages back to decimals with clear rules.
Minutes to Decimal Converter
Convert minutes and hours into decimal hours for payroll, billing, and timesheets.
Roman Numerals Converter
Convert numbers to Roman numerals and back, with a symbol-by-symbol breakdown.
Numbers to Words Converter
Convert any number into English words — plain, currency, or check-writing format — up to the quadrillions.
Decimal to Words Calculator
Write a decimal number in words three ways — said aloud digit by digit, as a fraction naming the place value (0.075 is seventy-five thousandths), and in cheque format.
Scientific Notation Calculator
Free scientific notation converter — turn any number into scientific, E, and engineering notation, and back to decimal.
Significant Figures Calculator
Free significant figures calculator — every digit marked up by why it does or does not count, with the genuinely ambiguous cases reported as a range rather than guessed at.
Geometry & Shapes
Geometry Calculator
Calculate area, perimeter, volume, and surface area for common 2D and 3D shapes.
Rhombus Calculator
Calculate the area, perimeter, diagonals, height, and angles of a rhombus from diagonals, side and angle, or side and height.
Stadium Calculator
Calculate the area and perimeter of a stadium shape (discorectangle) — a rectangle capped by two semicircles.
Hemisphere Calculator
Calculate the volume, curved surface, base area, and total surface area of a hemisphere from its radius.
Pyramid Calculator
Calculate the volume, surface area, slant heights, and lateral edges of a square or rectangular pyramid.
Prism Calculator
Calculate the volume, surface area, and diagonal of a rectangular prism (box) — or any prism from base area and length.
Triangular Prism Calculator
Calculate the volume and surface area of a triangular prism from the three triangle sides (Heron's formula) or base and height.
Rectangular Prism Calculator
Calculate the volume, surface area, and space diagonal of a rectangular prism (box) from length, width, and height.
Hypotenuse Calculator
Find the hypotenuse of a right triangle from its two legs using the Pythagorean theorem.
Right Triangle Side and Angle Calculator
Solve any right triangle for missing sides and angles from any two known values.
Radius of a Circle Calculator
Calculate the radius of a circle from its diameter, circumference, or area — with reverse calculations too.
Tube Volume Calculator
Calculate the material volume, inner capacity, and surface area of a tube (hollow cylinder) from its radii and length.
Ellipsoid Volume Calculator
Calculate the volume and approximate surface area of an ellipsoid from its three semi-axes a, b, and c.
Conical Frustum Surface Area Calculator
Calculate the total and lateral surface area, slant height, and volume of a conical frustum from its radii and height.
Slope & Distance Calculator
Free slope calculator — slope, distance, midpoint, angle, and line equation between any two points on a graph.
Random & Games
Random Number Generator
Generate random numbers within a custom range — integers or decimals, single or multiple, unique or repeating.
Lottery Number Generator
Generate random lottery numbers for Powerball, Mega Millions, EuroMillions, Lotto 6/49, or any custom draw — with jackpot odds.
Password Generator
Free password generator — create strong, random passwords locally in your browser with length, symbol, and look-alike options.
Dice Roller
Free dice roller — with the exact probability distribution of the total drawn first and your rolls landing on it, so you can see why “every total is equally likely” is wrong for anything past one die.
Time & World
Time Calculator
Add or subtract days, hours, minutes, and seconds across multiple time values, with day rollover handling.
Date Calculator
Find the exact time between two dates in years, months, weeks, and days — or add and subtract time from any date.
World Clock Calculator
Free world clock — compare local times across cities, see who is awake or at work, and find the meeting hour that works for everyone.
Countdown to Date Calculator
Free countdown to any date — live days, hours, minutes, and seconds remaining until a birthday, holiday, or event.