THE CALCULATOR BENCH / 05
One-rep max estimator
Compare Epley and Brzycki estimates from a recent set of 1–10 repetitions, with clear limits and metric or imperial load units.
01 / YOUR INPUTS
The initial values are an example. Change them to explore your own estimate. These inputs are not saved or sent to analytics.
02 / YOUR ESTIMATE
The two formulas give different estimates. Use a recent controlled set; this is not a recommendation to attempt a maximum lift.
Return to your training log ↗What the number means.
Epley estimates load × (1 + repetitions ÷ 30); Brzycki estimates load × 36 ÷ (37 − repetitions). At one completed repetition, both return the lifted load. We limit entry to 1–10 repetitions because prediction becomes less useful as fatigue and repetition counts increase.
The range is the disagreement between two formulas, not a statistical confidence interval. Technique, exercise and proximity to fatigue affect the estimate. It is unsuitable for comparing machine stacks or assisting someone with an injury.