One Rep Max Calculator
Estimate your maximum one-repetition weight limit (1RM) using Epley, Brzycki, and Lander formulas.
Estimated 1RM
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Predicted maxima are extrapolated from submaximal sets and lose accuracy above roughly ten repetitions. Attempting a true one-rep max carries genuine injury risk, so warm up thoroughly and use a spotter.Speak to a doctor or another qualified clinician about any health decision.Last reviewed .
Frequently asked questions
What is a One Rep Max (1RM)?
One Rep Max is the maximum amount of weight you can lift for a single repetition of a given exercise with proper form.
Which one-rep max formula is most accurate?
Epley and Brzycki are the most used and agree closely in the 3-10 rep range, which is where they are most reliable. Brzycki tends to read lower at high rep counts, Epley higher. Above about 10 reps every formula degrades badly, because endurance rather than maximal strength becomes the limiting factor.
Why should I estimate rather than test a true 1RM?
A true maximal attempt carries injury risk, requires spotters and competent technique, and needs a deload afterwards. Estimating from a set of 3-5 reps gives a number within a few percent for most lifters without any of that cost, which is why coaches program from estimated maxes for most of the training year.
How do I use my 1RM for programming?
Most strength programs prescribe percentages: roughly 85-95% for sets of 1-3, 75-85% for 4-6, and 65-75% for 8-12. Recalculate periodically, since a max from three months ago will under-prescribe if you have progressed. Percentages are a starting point - rate of perceived exertion on the day should still adjust the load.