Estimate one-repetition maximum from a submaximal set using six established formulas, then compare percentage-based training loads.
A one-repetition maximum is the greatest load completed once for a particular exercise under defined conditions. This calculator predicts it from weight and repetitions rather than encouraging a true maximal attempt.
Prediction accuracy varies by exercise, technique, proximity to failure, training experience, fatigue, and the number of repetitions completed.
1RM = W × (1 + R ÷ 30)1RM = W × 36 ÷ (37 − R)1RM = W ÷ (1.013 − 0.0267123R)1RM = W × R^0.101RM = W ÷ (0.522 + 0.419e^(−0.055R))1RM = W × (1 + 0.025R)For 100 kg completed for 5 repetitions, Epley estimates 116.67 kg. The calculator applies all six formulas, preserves their raw precision, and displays their arithmetic average as the main estimate.
For one repetition, the calculator explicitly treats the completed load as 1RM for every method, so 100 kg × 1 gives an average of 100 kg and a 100% training load of 100 kg.
An estimate for one exercise does not transfer directly to a different movement or technique.
Prediction uncertainty generally grows as repetitions increase; results above 10 repetitions deserve extra caution.
Rounded gym loads are practical equivalents, not changes to the underlying exact percentage.
The formulas use linear, exponential, power, and rational relationships derived from different samples and exercises. No equation is universally best.
The table multiplies the six-formula average by each percentage. Optional load rounding converts the exact value to a convenient gym increment in the selected unit.
A set must be representative for an estimate to be useful. Technique changes, assistance, fatigue, incomplete range of motion, and stopping far from failure can alter the result. High-repetition estimates are especially uncertain.
It is the greatest load completed once for a specific exercise under defined conditions.
No. This calculator exists to estimate 1RM from a submaximal set and does not recommend attempting a maximal lift.
They use different mathematical models and were developed from different data.
Lower-repetition sets generally provide more useful estimates. This calculator supports 1–20 and warns above 10.
Prediction equations are commonly based on repetitions-to-fatigue data. Stopping early can underestimate capacity.
No. They are descriptive load references only.
Available plates may not match the exact calculated value, so rounding provides a practical equivalent.
They can view estimates, but technique consistency and appropriate supervision are important.
Formula and validation literature.