One Rep Max Calculator

Estimate the heaviest weight you could lift for one rep, without actually testing it, from a set you've already done. Use it to pick your training weights.

kg

A set of 2 to 10 reps gives the best estimate.

Enter your details to see your result.

These numbers are estimates for healthy adults, not medical advice. If you have a health condition, are pregnant or are under 18, speak to a doctor first.

How it works

We average two well-known formulas, Epley and Brzycki, to estimate your one rep max from the weight you lifted and the number of reps you did with good form.

Estimates are most accurate for sets of 2 to 10 reps. With more reps, endurance starts to matter more than strength and the estimate drifts.

The table shows weights at different percentages of your max and roughly how many reps you can do with each. For building muscle, most of your sets can sit around 65 to 85% of your max.

Questions

What is a one rep max?

Your one rep max (1RM) is the heaviest weight you can lift once with good form, for an exercise like the bench press, squat or deadlift.

Is it safe to test my real one rep max?

It can be, with a spotter, a good warm-up and safety bars, but beginners don't need to. An estimate from a set of 3 to 8 reps is safer and accurate enough.

Which lifts does this work for?

Big barbell and dumbbell lifts such as the bench press, squat, deadlift, overhead press and rows. It is less useful for small exercises like curls and raises.

How do I use my one rep max in training?

Pick a percentage from the table for the reps you want. For example, about 75% of your max for sets of 8 to 10.

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