One Rep Max Calculator
Calculate your one rep max (1RM) using multiple proven formulas. Enter the weight and reps you performed to estimate your maximum single-rep strength.
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Frequently Asked Questions
What is a one rep max (1RM)?▾
A one rep max is the maximum amount of weight you can lift for a single repetition with proper form. It is the gold standard for measuring maximal strength in weightlifting.
How accurate are 1RM calculator formulas?▾
One rep max formulas are most accurate with rep counts between 2 and 10. This calculator uses five proven formulas (Epley, Brzycki, Lander, Lombardi, and Mayhew) and averages them for a more reliable estimate.
How do I use my 1RM for training?▾
Use the percentage chart to plan your training loads. For strength, train at 85-100% of your 1RM for 1-5 reps. For muscle growth (hypertrophy), use 65-84% for 6-12 reps. For endurance, use 50-64% for 13-20+ reps.
Is it safe to test my actual one rep max?▾
Testing a true 1RM carries injury risk, especially without a spotter. This calculator lets you estimate your 1RM from submaximal lifts, which is safer and still very useful for programming your training.