Rep Max Calculator
A one-rep max is the most weight you could lift once. Few people test it directly, so this estimate works it out from a set of reps you have already done.
- Free
- Works offline after your first visit
- Saves on this device
- No sign-up
- Updated
How it works
This uses the Brzycki formula. The estimated one-rep max is the weight lifted times 36, divided by 37 minus the number of reps.
Estimates are most useful for sets of about 2 to 10 reps. Sets with many reps, or sets taken near failure, give less dependable numbers. Use the result for planning, not as a number to test alone.
Worked example
Lifting 185 lb for 5 reps suggests a one-rep max of about 208 lb.
Questions
Can I test my real one-rep max instead?
You can, but do it with a warm-up and a spotter, and build up gradually. Many people estimate because a true max test is hard on the body.
Which reps give the best estimate?
Sets of 2 to 10 reps give the most reliable results. The input stops at 12, where the estimate is less certain.
Does one formula fit every lift?
No. Strength differs from one lift to another, so an estimate for a squat may not match the same numbers on a curl.
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