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Percentage of 1-Rep Max from Reps to Failure Calculator

% of 1RM implied by the weight lifted and reps achieved.

Estimates the percentage of 1-rep maximum using the Brzycki formula: % 1RM = 100 / (1.0278 − 0.0278 × reps). Useful when you don't test 1RM directly.

Priya Venkatesan By Priya Venkatesan
Published Last reviewed 1 min read

Inputs

kg

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

%1RM = 100 / (1.0278 − 0.0278·reps)

In depth

Estimates the percentage of 1-rep maximum using the Brzycki formula: % 1RM = 100 / (1.0278 − 0.0278 × reps). Useful when you don't test 1RM directly.