1 Rep Max

Your one-rep max (1RM) is the heaviest weight you could lift once with good form. Testing it directly is risky and fatiguing, so lifters estimate it from a set taken to (or near) failure at a lighter weight. The calculator lets you choose between the two most-cited estimation formulas, Epley and Brzycki, and shows a training table of loads from 95% down to 50% of the estimate.

Epley and Brzycki

Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight ÷ (1.0278 − 0.0278 × reps), which is the same as weight × 36 ÷ (37 − reps). The two agree closely up to about 5 reps and diverge as reps climb; Brzycki is usually preferred for sets of 7–10. Neither is reliable past 10–12 reps, because at that point muscular endurance rather than maximal strength limits the set. The calculator accepts up to 30 reps but does not warn you when the estimate becomes unreliable, so keep test sets short.

When to use this calculator

Use it to set working weights for percentage-based programmes (5/3/1, linear progression, most powerlifting templates) without maxing out. Re-test every 4–8 weeks with a 3–5 rep set to keep the estimate current. Use the same lift, the same equipment and a fully rested state; a rep max taken at the end of a long session underestimates your true max. Beginners should treat the number as a guide, since technique changes quickly enough that estimates drift week to week.

Worked example

You squat 100 kg for 5 clean reps. Epley gives 100 × (1 + 5 ÷ 30) = 116.7 kg; switching to Brzycki gives 100 ÷ (1.0278 − 0.139) = 112.5 kg. Using the Epley figure, a programme calling for 3 sets of 5 at 80% would use about 93 kg, and a heavy triple at 90% about 105 kg; the training table on the page lists these percentages for you.

Frequently asked questions