$ TOOL · ONE REP MAX CALCULATOR

Estimate your 1RM from a real set.

Enter a weight and the reps you completed. This one rep max calculator uses the Epley formula, then turns the estimate into useful training percentages.

ESTIMATED 1RM
117 kg

Best used with clean sets of 2-8 reps. A true max is still tested under the bar.

$ TRAINING PERCENTAGES

Use the estimate without maxing today.

95% 111 kg
90% 105 kg
85% 99 kg
80% 94 kg
75% 88 kg
70% 82 kg
65% 76 kg
60% 70 kg

How this 1RM calculator works

The calculator uses the Epley formula: 1RM = weight x (1 + reps / 30). It is a practical estimate, not a guarantee. A set of 5 at 100 kg estimates a 117 kg one-rep max; a set of 10 estimates 133 kg, but higher-rep predictions depend more on conditioning and technique.

For beginner programs, the estimate is most useful for setting conservative starting weights and training percentages. If you are still adding weight every session, pair this with the novice linear progression guide and the plate calculator.

One rep max FAQ

How accurate is a one rep max calculator?

Most accurate for clean sets of 2 to 8 reps. Past 10 reps, conditioning changes the estimate.

Should beginners test a true 1RM?

Usually no. Beginners get better data from clean sets of 3 to 8 reps while technique is still improving.