One-Rep Max (Average) Calculator

About this calculator

A one-rep max (1RM) is the heaviest weight you can lift for a single complete repetition, but testing it directly is risky and impractical for most training days, so strength coaches estimate it from a lighter set taken to near-failure using regression formulas built from decades of lifting data. The four most established are the Epley formula (1RM = weight × (1 + reps/30)), the Brzycki formula (1RM = weight × 36/(37 − reps)), the Lombardi formula (1RM = weight × reps^0.10), and the Lander formula — each derived from different populations and rep ranges, which is why they can disagree by a few percent on the same set.

Because no single formula is universally most accurate across all rep ranges and lifters, averaging all four gives a more balanced, less formula-dependent estimate — a practice strength and conditioning coaches use when programming percentage-based training (like 5/3/1 or linear periodization) without requiring an athlete to actually max out and risk injury or excessive fatigue.

This calculator takes the weight and reps from a recent set and applies all four formulas, then averages them to give you a single, more reliable 1RM estimate for programming your training percentages.