How accurate is an estimated 1RM?

For sets of about 2 to 10 reps it is quite accurate. Above 10 reps the estimate becomes less reliable because endurance plays a bigger role.

What are the percentages for?

Many strength programs prescribe weights as a percentage of your 1RM. The table converts your estimated max into weights for common rep targets.

Which formula should I use?

Epley and Brzycki are both estimates. Compare them and track the same formula over time rather than treating either value as a guaranteed safe maximum.

Health & Fitness

One Rep Max Calculator

Estimate your one-rep max (1RM) from a lift and see training weights by rep count.

Free browser toolRuns in your browserNo sign-up

Weight liftedRepetitions

Estimated 1-rep max (Epley)

Brzycki formula: 68. Estimates are most accurate for sets of 10 reps or fewer.

Training weights by reps

1 rep (100%)70

2 reps (95%)67

3 reps (90%)63

5 reps (87%)61

6 reps (85%)60

8 reps (80%)56

10 reps (75%)53

12 reps (70%)49

15 reps (65%)46

About the One Rep Max Calculator

Your one-rep max (1RM) is the most weight you can lift for a single repetition. This calculator estimates it from a set you have already done, so you do not have to attempt a risky max lift.

It uses the Epley formula for the main estimate and shows the Brzycki formula too, plus a handy table of suggested training weights for different rep ranges (as percentages of your 1RM).

Estimates are most accurate for sets of ten reps or fewer. Everything is calculated in your browser.

Key features

Epley and Brzycki estimates
Training weights by rep percentage
No risky max attempt needed
Private, in-browser calculation

How to use

1Enter the weight you lifted.
2Enter how many reps you completed.
3Read your estimated 1RM and training weights.

Examples

Five-rep set

Input: 100 kg for 5 repetitions

Output: Epley 1RM about 116.7 kg; Brzycki about 112.5 kg

The two formulas use different curves, so the calculator displays both estimates.

Frequently asked questions

How accurate is an estimated 1RM?: For sets of about 2 to 10 reps it is quite accurate. Above 10 reps the estimate becomes less reliable because endurance plays a bigger role.
What are the percentages for?: Many strength programs prescribe weights as a percentage of your 1RM. The table converts your estimated max into weights for common rep targets.
Which formula should I use?: Epley and Brzycki are both estimates. Compare them and track the same formula over time rather than treating either value as a guaranteed safe maximum.

Open a related tool to prepare your files or refine the finished result.