One Rep Max Calculator

Enter your heaviest recent set. The board estimates the most you could lift for a single.

Weight lifted Reps (1 to 15)

Estimated 1RM

kg (average of three formulas)

Epley-

Brzycki-

Lombardi-

Sets of 10 reps or fewer give the tightest estimate. A completed single is not an estimate, it IS your max.

Training Percentages From Your Max

Most strength programs write sets as a percentage of 1RM. Once the board shows a number, this table converts it into working weights.

% of 1RM	Weight (kg)	Typical use
Type a weight and reps above and this table fills itself.

The three formulas

Epley: 1RM = w × (1 + r / 30). Brzycki: 1RM = w × 36 / (37 - r). Lombardi: 1RM = w × r^0.10.

Worked example: 100 kg for 5 reps. Epley says 116.7, Brzycki says 112.5, Lombardi says 117.5. The board averages the three to 115.5 kg. Showing all of them beats picking a favorite, because each formula was fit to different lifters on different lifts.

Accuracy and limits

These are population curves, not a promise about your body. They agree closely up to about 10 reps, then drift apart, and past 15 reps the math turns to guesswork. That's why the reps field stops at 15.

Enter 1 rep and every formula returns your weight unchanged: a single you actually locked out needs no estimating. The kg and lbs buttons only relabel the output, since the formulas don't care which unit you lift in.

Got a target for your next session? The plate calculator turns it into plates on the bar. These numbers are arithmetic, not coaching, see the disclaimer.