One rep max calculator

Updated 16 July 2026

Enter the weight you lifted and the reps you got, and this calculator estimates your one rep max (1RM) using the two most widely used and validated formulas, Epley and Brzycki. A set of 2 to 6 hard reps gives the most accurate estimate.

Your 1RM is the anchor number for strength programming: working weights are set as percentages of it, so a good estimate means every set of your plan is pitched at the right effort.

Units

Estimated one rep max

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Enter a weight and reps to see your estimate.

Training loads from your estimated max
Percent of 1RM Weight Typical rep target
95% … 2 reps
90% … 3 to 4 reps
85% … 5 to 6 reps
80% … 7 to 8 reps
75% … 9 to 10 reps
70% … 11 to 12 reps
65% … 13 to 15 reps

Calculators for specific lifts

The maths is the same for every exercise, but test set advice differs by lift. These pages cover the details for the big three.

How to calculate your one rep max

  1. 1 Do a hard test set Pick a weight you can lift for 2 to 6 clean reps and take the set close to failure. Fewer reps give a more accurate estimate than a long, grindy set.
  2. 2 Enter the weight and reps Type the weight you lifted and the number of reps you completed into the calculator.
  3. 3 Read your estimated 1RM The headline number is the average of the Epley and Brzycki formulas. Use it as the anchor for your training percentages.

How this is calculated

We estimate your max with the two most widely used and validated equations and show their average as the headline number. The Epley formula is weight × (1 + reps ÷ 30). The Brzycki formula is weight × 36 ÷ (37 minus reps). For a single rep both return the weight itself, and for 2 to 6 reps they typically agree within 2 to 3 percent.

The training load table applies standard percentage guidelines to your estimated max. Percentages and rep targets are a starting point, not a rule: bar speed, technique, and how you recover matter as much as the arithmetic.

Common questions

What is a one rep max?

Your one rep max is the heaviest weight you could lift for a single rep with sound form. Most people never test it directly; they estimate it from a submaximal set, which is exactly what this calculator does.

Which formula should I trust, Epley or Brzycki?

Both are well validated and agree within a few percent for sets of 2 to 6 reps. Epley reads slightly higher at 8 or more reps, Brzycki slightly lower. We show both so you can see the honest range rather than a single false precision number.

How many reps should my test set have?

Estimates are most accurate from a hard set of 2 to 6 reps. Above 10 reps the relationship between reps and max strength gets noisy, so treat those estimates as a rough guide.

Do I ever need to test a real 1RM?

Not for programming. Training percentages work fine off an estimated max, and skipping true max attempts removes the riskiest lifts from your training. Competitive powerlifters are the main exception.

Next Is your max any good? See where your lift ranks, from beginner to world class, with the strength standards calculator.

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