Force Calculator
Free force calculator using Newton's second law F = ma — solve for force, mass, or acceleration, with an animated illustration.
Everyday Uses
Physics homework
Apply Newton's second law F = ma and solve for force, mass, or acceleration.
Thrust & motion
Work out the force needed to accelerate a car, rocket, or trolley to a target rate.
Weight vs mass
Convert between mass and weight with W = m·g on Earth or any other planet.
Engineering loads
Estimate the forces on ropes, beams, and joints from accelerating masses.
Frequently Asked Questions
What is the formula for force?
Newton's second law states force equals mass times acceleration: F = m × a. Mass is in kilograms, acceleration in m/s², and force in newtons (N). A 2 kg object accelerating at 5 m/s² needs F = 2 × 5 = 10 N. Rearranged, m = F ÷ a and a = F ÷ m.
What is one newton?
One newton (N) is the force that gives a 1 kg mass an acceleration of 1 m/s². It is equivalent to 1 kg·m/s². For reference, holding a small apple takes roughly 1 N; the weight of a 1 kg bag of sugar is about 9.81 N (its mass times gravity).
How is force related to weight?
Weight is simply the force of gravity on a mass: W = m × g, where g = 9.81 m/s² on Earth. So a 10 kg object weighs about 98.1 N. Weight changes with gravity (less on the Moon), but mass stays the same everywhere.