Estimate your 1RM from a working set. The Epley formula handles 1–10 reps (where it's most accurate). Lombardi handles 11–15 reps with reduced accuracy. Above 15 reps the calculator won't return a number because the formulas break down.
This calculator estimates your 1RM from a working set. Only enter a weight you can lift with good form. The estimate is a guide for programming.
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Enter a weight and rep count, then hit estimate. The percentage table will fill in below.
Safety note. Working at 90%+ of 1RM requires a spotter, safety pins, or both. Working above 90% carries a higher injury risk and is for advanced lifters only. If your form breaks, the rep doesn't count and the weight is too heavy. This calculator can be used to estimate 1RM without having to go beyond 90% yourself.
Whole-session 1RMs.
Log every lift from a session — an estimated 1RM appears live for each one. Open "See more data" on any lift for its full percentage breakdown, from max-strength singles down to speed work.
ExerciseWeight (kg)RepsRIREst. 1RM
Read before trusting the numbers
These rep figures are population averages based on NSCA data. Your actual reps at any percentage vary with the exercise (you'll manage more reps on a leg press than a bench press) and your individual physiology. Use them as a starting point and adjust from what you see in your own training.
A 1RM estimate is only as good as the effort behind it. The working set should be taken close to genuine failure — but only with a weight you can control safely.
Only log reps in reserve if you can judge it honestly. Overestimating how many reps you had left inflates your 1RM and throws off every number below it.
A rep only counts if form held. A grinding, form-breaking rep means the weight was too heavy and the estimate stops being meaningful.
Estimates from low-rep sets (around 3–5) are far more accurate than from high-rep sets. Above 15 reps the formulas break down, so the calculator won't return a number.