One Rep Max Calculator

How It Works

One-rep max formulas answer the same question from a submaximal set — how much could this lifter have moved for one rep? This tool shows three published curves side by side, because no single one is "the truth".

The Three Formulas

Epley, 1RM = w × (1 + r/30), is the simple linear one — every extra rep adds about 3.3% to the estimate. Brzycki, 1RM = w × 36 ÷ (37 − r), curves the other way: each additional rep subtracts a growing slice, so it caps lower at high rep counts. Lombardi, 1RM = w × r^0.10, sits between them with a smooth power curve. For 100 kg × 5 reps the three give roughly 116.7, 112.5 and 112.2 kg — the mean shown in the highlighted card is the most defensible single number.

Why Under 10 Reps

All three assume the set ended because the weight was heavy. Past about 10 reps, sets often end from cardiovascular fatigue or local muscular endurance long before true maximal strength is the limiter — so the formulas start disagreeing wildly and over-reading the 1RM. That is why the input stops at 15 with a warning past 10: single-digit reps with a hard set are the zone where the estimates are worth anything (±5–10%).

What the Table Is For

Percent-of-1RM tables are the backbone of linear and undulating programming: 85% for heavy fives, 75% for volume work, 60–65% for speed and technique days. The target-rep column lists the reps that percentage typically supports for a trained lifter — treat it as the expected working range for that load, not a test you must hit.

Frequently Asked Questions