One Rep Max Calculator
Estimate your one-rep maximum (1RM) from a set you completed at sub-max weight. Uses Epley and Brzycki formulas — the two most popular in strength training.
Inputs
The load on the bar (or machine), any unit.
Most accurate for 2-10 reps. Above 10, estimates drift.
Estimated 1RM (average)
—
Epley estimate
—
Brzycki estimate
—
95% (heavy)
—
85% (working sets)
—
70% (volume)
—
About One Rep Max Calculator
Why two formulas?
Epley (1985) is straightforward and slightly aggressive. Brzycki (1993) is more conservative for higher rep ranges. Most lifters average them; competitive powerlifters often test a true 1RM in the gym instead.
Best rep range for accuracy
2-6 reps. As rep count rises, the assumed strength curve breaks down — a 20-rep set at any weight tells you more about endurance than max strength.
Use cases
Programming percentage-based training. Tracking strength gains over time. Comparing lifters at meets in different weight classes (via Wilks/IPF coefficients applied to 1RM). Estimating a starting weight when trying a new lift.