One Rep Max Calculator
Estimate your one-rep max (1RM) from the weight and reps of any set. Compare 7 proven formulas, see your full rep-max table and training percentages — accurate, instant and free.
Estimated rep maxes
Formula comparison
One Rep Max Calculator — estimate your one-rep max 1RM (2026)
A one-rep max (1RM) is the most weight you can lift for a single rep, and it is the foundation of smart strength programming. This free one rep max calculator estimates your 1RM from any set — just enter the weight and how many reps you completed. It works for the bench press, squat, deadlift, overhead press and any other barbell or machine lift.
How the one rep max calculator works
Testing a true single is risky and hard to program around, so lifters estimate it. This calculator applies seven validated formulas — including Epley (1RM = weight × (1 + reps ÷ 30)) and Brzycki — and averages them for a reliable number. Fewer reps give a better estimate, so a heavy set of 2–5 predicts your max far more accurately than a set of 15.
Turn your 1RM into training weights
Once you know your 1RM you can train at the right intensity: strength work sits around 85–95% of 1RM for low reps, hypertrophy around 67–80%, and muscular endurance below 67%. The rep-max table converts your max into a working weight for every rep range.
One rep max calculator — frequently asked questions
Which 1RM formula is the most accurate?
No single formula wins for everyone, which is why this tool defaults to the average of seven. Epley and Brzycki are the most widely used; they agree closely at low reps and diverge as reps climb.
Can I use this one rep max calculator for any exercise?
Yes. The maths works for any free-weight or machine lift — bench, squat, deadlift, overhead press, rows and more. Estimates are most reliable on big compound lifts performed for low reps.
What is a one-rep max (1RM)?
Your one-rep max is the heaviest weight you can lift for a single repetition with good form. It is the standard measure of maximal strength and the reference point for setting training percentages.
How many reps should I use for the best estimate?
Use a challenging set you took close to failure at 2–6 reps. That range balances accuracy and safety — heavy enough to predict your max well, light enough to perform without undue risk.
Is it safe to test my true one-rep max?
Maximal singles carry more injury risk and need a thorough warm-up and ideally a spotter. For most lifters, estimating your 1RM with a calculator is safer and accurate enough for programming.