Estimated 1RM from a weight you can lift for a few reps.
Estimated one-rep max
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Percent of 1RM by reps
Reps
% of 1RM
Weight
An estimate from a formula, not a substitute for an actual tested max. Accuracy drops for sets beyond about 10-12 reps — test closer to your true max for an important number. Near-maximal lifts carry real injury risk — talk to a doctor before attempting one if you are new to strength training or have a health condition.
Both formulas are estimates from rep-max studies, not a substitute for an actual tested max — expect them to differ from each other and from reality by a few percent.
Brzycki tends to estimate slightly lower than Epley at higher rep counts; the two agree most closely around 5 reps.
Accuracy drops the further you get from a true near-max effort — a set of 3-5 reps taken close to failure gives a better estimate than a set of 15.
Which formula should I use?
They typically land within a few percent of each other for rep ranges up to about 10. Epley is very slightly more common in strength-training contexts; neither is definitively more accurate for every lifter.
Why does the calculator reject high rep counts?
The Brzycki formula breaks down mathematically at 37 reps (dividing by zero), and both formulas become unreliable well before that — high-rep sets do not translate cleanly to a maximal single-rep effort.
How do I use the percent-of-1RM table?
It shows roughly what weight to use for a target rep count based on your estimated max — useful for programming work sets without having to test a new true max every time.
Is it safe to test my actual one-rep max?
It carries more injury risk than submaximal training, especially without a spotter or for lifters new to a movement. Most programs only test a true 1RM occasionally, with a proper warm-up and safety equipment, and use an estimate like this calculator the rest of the time.