One Rep Max Calculator

Calculate your estimated one-rep maximum (1RM) based on your performance with submaximal weights. Choose from multiple formulas and view detailed rep ranges and percentage breakdowns.

1RM Formulas Explained

Epley Formula

Most commonly used formula for estimating 1RM from submaximal loads.

1RM = Weight × (1 + Reps/30)

Brzycki Formula

Popular formula that tends to be more accurate for higher rep ranges.

1RM = Weight × (36/(37-Reps))

Lombardi Formula

Power-based formula that may be more accurate for explosive movements.

1RM = Weight × Reps^0.1

Important Notes

• 1RM estimates are most accurate when using 1-5 repetitions

• Higher rep ranges (6-10) may overestimate your actual 1RM

• Individual factors like muscle fiber type and training experience affect accuracy

• Always warm up properly before attempting true 1RM lifts