How to calculate your one-rep max
For a lifter who benched 185 lbs for 5 clean reps
- The set you did
- 185 lbs for 5 reps
- Estimated one-rep max
- about 208 lbs
- 90 percent (a heavy triple)
- about 187 lbs
- 75 percent (a set of about 10)
- about 156 lbs
Opens the One Rep Max. Free, no account needed.
Your one-rep max is the most you could lift for a single rep, but you almost never need to actually test it. You can estimate it from a set you already did, and for most people that is a much better trade of risk for information.
The calculator uses the Brzycki formula, which takes the weight you lifted and the number of reps and works backward to a single-rep estimate. In the example above, 185 pounds for five clean reps points to a 1RM around 208 pounds. From there it fills in a percentage chart, so you can see that a heavy triple sits near 187 pounds and a working set of ten lands around 156.
Why bother estimating it: most strength programs prescribe weight as a percentage of your 1RM, so you need a number to do the math from. An estimate is plenty for that. I would much rather you train off a good estimate than burn a session, and take on the injury risk, chasing the exact figure.
Two tips for a clean estimate. Use a set in the three to five rep range, because the formula is most accurate there and drifts past ten reps. And retest every four to eight weeks, especially early on when this number moves fast, so your working weights keep up with you.
Put in a recent set to get your estimate and full percentage chart.
Not sure where to start?
The home page calculator gives you your real numbers in one place: the calories to aim at, a macro split, and a few things to do this week. Free, no account needed to see it.
Find where to startIf you would rather someone build this around your life instead of guessing, my 1:1 coaching is there. The free tools get you most of the way.