One Rep Max (1RM) Calculator
Estimate your one-rep max from any set using Epley, Brzycki, Lombardi, and O'Conner formulas — with training percentages.
Everyday Uses
Program percentages
Your program says "squat at 80%"— get the actual barbell weight from any recent hard set.
Progress tracking without max attempts
Re-estimate your 1RM monthly from working sets — watch strength climb without risky max-outs.
Realistic goal setting
Chasing a 100 kg bench? See how close your current sets put you and what's left.
Safer training
Get 1RM numbers for programming without actually attempting a true max — especially valuable for newer lifters.
Frequently Asked Questions
What is a one-rep max (1RM)?
Your 1RM is the heaviest weight you can lift for exactly one repetition with proper form. It is the standard benchmark for strength and the anchor for percentage-based training programs — "squat 5×5 at 80%" means 80% of your 1RM. Estimating it from a submaximal set is safer than testing it directly.
How accurate are 1RM formulas?
Quite accurate in the 2–10 rep range — typically within 2–5% for trained lifters. Accuracy drops as reps climb, which is why this calculator caps input at 15. The four formulas (Epley, Brzycki, Lombardi, O'Conner) diverge slightly by rep range, so the average of all four is a robust estimate.
How do I use the training percentage table?
Strength programs prescribe loads as percentages of 1RM: roughly 85–95% for strength work (2–6 reps), 70–85% for hypertrophy (6–12 reps), and 60–70% for endurance and technique work. The table converts your estimated max into actual barbell weights for each zone.
Is it safe to test my true 1RM?
Testing a true max puts high stress on joints and connective tissue and should only be done well-warmed-up, with a spotter or safety pins, and ideally with significant training experience. For most lifters, estimating from a hard set of 3–5 reps gives the programming benefits without the risk — that is exactly what this calculator is for.