One-Rep Max Calculator

The Epley and Brzycki formulas are both widely used estimation methods that produce slightly different results, especially at higher rep counts — showing both gives you a realistic range rather than presenting a single estimate as more precise than it actually is. Neither formula is "more correct" than the other; they're both statistical approximations.

These formulas are most accurate for rep ranges of 1-10 and become progressively less reliable above 10-12 reps, since the relationship between reps and percentage of max isn't perfectly linear at very high rep counts — treat the estimate as a useful training guide, not a substitute for an actual tested max if precision matters (like for powerlifting meet planning).

Many strength programs prescribe working sets as a percentage of your 1RM (like "3 sets of 5 at 80% of 1RM") — the table converts your estimated 1RM into the actual weight to load for each common percentage, saving you from doing that math manually before every session.

If you already lifted 1 rep, that weight *is* your actual one-rep max by definition — no formula/estimation is needed in that case, so the calculator skips the estimation math entirely when reps equals 1.