One-rep max calculator
Five published formulas, shown together. They disagree, and the size of that disagreement is the most useful thing on this page.
Every weight, worked out
Each of these opens a page with the five estimates, a percentage table and a warm-up ramp for that exact set. Reps two to twelve are linked from inside each page.
Kilograms — at five reps
20 kg · 25 kg · 30 kg · 35 kg · 40 kg · 45 kg · 50 kg · 55 kg · 60 kg · 65 kg · 70 kg · 75 kg · 80 kg · 85 kg · 90 kg · 95 kg · 100 kg · 105 kg · 110 kg · 115 kg · 120 kg · 125 kg · 130 kg · 135 kg · 140 kg · 145 kg · 150 kg · 155 kg · 160 kg · 165 kg · 170 kg · 175 kg · 180 kg · 185 kg · 190 kg · 195 kg · 200 kg · 210 kg · 220 kg · 230 kg · 240 kg · 250 kg · 260 kg · 270 kg · 280 kg · 290 kg · 300 kg
Pounds — at five reps
95 lb · 115 lb · 135 lb · 155 lb · 175 lb · 185 lb · 195 lb · 205 lb · 225 lb · 245 lb · 265 lb · 275 lb · 285 lb · 315 lb · 335 lb · 365 lb · 405 lb
How the formulas work
Every rep-max formula is a curve fitted to a group of people, then applied to you. They agree closely at three to five reps, which is what they were built on, and drift apart fast above ten — by twelve reps the spread between the highest and lowest estimate is routinely 10%.
So the honest output is a range. If four formulas say 110 to 118 kg, your max is somewhere in there, and the way to find out precisely is to work up to it under a spotter, not to trust a page.
| Formula | Published |
|---|---|
| Epley | Epley, 1985 |
| Brzycki | Brzycki, 1993 |
| Lombardi | Lombardi, 1989 |
| O'Conner | O'Conner et al., 1989 |
| Mayhew | Mayhew et al., 1992 |
SOURCE·Published formulae — Epley, Brzycki, Lombardi; IPF GL and DOTS coefficients·REVIEWED JUL 2026