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One-Rep Max Calculator — Free Online Calculator

Estimates your 1RM for strength training from reps and weight lifted.

What is it?

The one-rep max (1RM) calculator estimates the maximum weight you can lift for a single repetition from a sub-maximal lift, using the Epley formula.

Formula

Epley: 1RM = weight × (1 + reps / 30) Percentage of 1RM: working weight = 1RM × (% / 100)

Example

Bench press: lifted 90 kg for 5 reps. 1RM = 90 × (1 + 5/30) = 90 × 1.167 ≈ 105 kg. At 80%: working weight = 105 × 0.80 = 84 kg.

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