One-rep max calculator
Three standard formulae, shown side by side rather than blended into one number. When they disagree by six percent, that gap is the most useful thing on the page. Averaging it away just hides it.
RPE 10 means the set was taken to failure. Every point below is one rep still in the tank, so a triple at RPE 8.5 is treated as a 4.5-rep max, a very different estimate from a triple that nearly stapled you.
Training percentages
What the formulae actually do
- Epley:
w × (1 + r/30). Runs high at higher reps. Undefined at a single, so a single returns the weight itself. - Brzycki:
w × 36 / (37 − r). Collapses entirely as reps approach 37; we refuse to answer past 36 rather than print a number. - Lombardi:
w × r0.10. The flattest of the three.
All three were fitted to populations, not to you. Past about five reps they are an educated guess with decimals attached, which is why the spread is shown rather than hidden.