1RM Calculator

Estimate your one-rep max from a recent set: enter the weight lifted and the number of reps completed, and get your training percentages instantly.

Estimated 1RM

114.6kg

Average estimate

Epley Formula: 116.7 kg
Brzycki Formula: 112.5 kg

These are estimates. Never attempt a true 1RM without a spotter and a thorough warm-up.

Working weights by % of 1RM

95%108.9 kg
90%103.1 kg
85%97.4 kg
80%91.7 kg
75%86 kg

70%80.2 kg
65%74.5 kg
60%68.8 kg
55%63 kg
50%57.3 kg

Create your free program and track your weights, with AI analysis in Max

Max load

What is a 1RM?

Your 1RM (one-rep max) is the heaviest weight you can lift once with proper form. Coaches program most workouts as a percentage of this max: light percentages for technique and volume, heavy for strength. The Epley and Brzycki formulas estimate your 1RM from a submaximal set, without ever having to test a true max. Estimates are most reliable for sets of 10 reps or fewer.

Calculator formulas

The calculator applies two recognized formulas and displays their average. Epley: 1RM = load × (1 + reps / 30). Brzycki: 1RM = load × 36 / (37 - reps).

Example: lifting 100 kg 5 times gives 116.7 kg with Epley and 112.5 kg with Brzycki, for an estimated average of 114.6 kg.

These estimates are most reliable up to about 10 reps. Beyond that, the gap between the estimate and your true max grows.

Sources

Epley B. Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises; 1985.
Brzycki M. Strength Testing: Predicting a One-Rep Max from Reps-to-Fatigue. Journal of Physical Education, Recreation & Dance. 1993;64(1):88-90. doi:10.1080/07303084.1993.10606684

1RM percentage by number of reps

1RM percentage by number of reps
Reps completed	% of estimated 1RM (Epley)
1	100%
2	94%
3	91%
4	88%
5	86%
6	83%
8	79%
10	75%
12	71%

Your questions

Do I need to test my maximum load to use the calculator?

No. Enter a load and the number of repetitions you completed. The formulas estimate your maximum for one repetition without requiring a maximal attempt.

Why show two formulas?

Epley and Brzycki use two different relationships between load and repetitions. Their difference shows that the result is an estimate. The displayed average is also an estimate.

How do I use the load table?

The table applies different percentages to your estimated 1RM. Use these values as guidelines and adjust your load based on the quality of your repetitions and the effort you feel during your workout.

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