One Rep Max Calculator
Enter a recent lift and the reps you completed to estimate your one-rep max across five validated formulas, with a percentage table for strength programming.
Average estimated 1RM
115.1 kg
Epley formula
116.7 kg
Brzycki formula
112.5 kg
Lombardi formula
117.5 kg
O'Conner formula
112.5 kg
Training percentages
How to Use the One Rep Max Calculator
- Enter the weight you lifted and how many clean reps you performed (1-12).
- Compare 1RM estimates from the Epley, Brzycki, Lombardi, O'Conner and Wathan formulas.
- Use the percentage table (95%, 90%, 85%...) to program working sets.
Formulas Used
Epley: 1RM = weight × (1 + reps / 30)
Brzycki: 1RM = weight × 36 / (37 − reps)
Lombardi: 1RM = weight × reps^0.10
O'Conner: 1RM = weight × (1 + 0.025 × reps)
Wathan: 1RM = 100 × weight / (48.8 + 53.8 × e^(−0.075 × reps))
Frequently Asked Questions
Why not just test my true 1RM?
True max testing carries injury risk and heavy fatigue costs. Estimating from a hard set of 3-6 reps is safer, nearly as accurate, and easier to recover from.
How many reps give the most accurate estimate?
Sets of 3-5 reps at heavy load are most accurate. Accuracy drops noticeably beyond about 10-12 reps because muscular endurance starts to limit performance more than strength.
What percentages should I train at?
Common schemes: 90-95% for peaking singles, 80-87% for strength work at 3-5 reps, and 65-75% for hypertrophy sets of 8-12 reps.
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