One Rep Max Calculator
Calculate your one-rep maximum for strength training and powerlifting using proven formulas.
Calculate Your 1RM
Enter the weight lifted and reps performed.
Most commonly used, good for 2-10 reps
Weight Unit
Training Load Chart
Calculate your 1RM to fill in the recommended working weight for each training goal.
| % of 1RM | Weight (lbs) | Reps | Purpose |
|---|---|---|---|
| 95% | — | 1-2 | Max Strength |
| 90% | — | 2-4 | Max Strength |
| 85% | — | 4-6 | Strength |
| 80% | — | 6-8 | Strength |
| 75% | — | 8-10 | Hypertrophy |
| 70% | — | 10-12 | Hypertrophy |
| 65% | — | 12-15 | Muscular Endurance |
| 60% | — | 15+ | Muscular Endurance |
About the 1RM Formulas
- Epley Formula
weight × (1 + reps ÷ 30)— Most commonly used, good for 2-10 reps- Brzycki Formula
weight × 36 ÷ (37 − reps)— Conservative estimate, good for 2-10 reps- Lander Formula
weight × 100 ÷ (101.3 − 2.67123 × reps)— Good for higher rep ranges- Lombardi Formula
weight × reps^0.10— Simple power formula- Mayhew Formula
weight × 100 ÷ (52.2 + 41.9 × e^(−0.055 × reps))— Good for bench press- O'Conner Formula
weight × (1 + 0.025 × reps)— Simple linear formula
Important Safety Notes
• Always warm up properly before attempting heavy lifts.
• Use a spotter when attempting near-maximum weights.
• These are estimates - actual 1RM may vary based on training, fatigue, and technique.
• Do not attempt a true 1RM more than once every 4-6 weeks.
• Consider using these estimates for programming rather than testing your actual 1RM.
Frequently Asked Questions
Sources & references
- Epley, B. (1985). Boyd Epley Workout, University of Nebraska — origin of the Epley formula: 1RM = weight × (1 + reps ÷ 30).
- Brzycki, M. (1993). Strength testing — predicting a one-rep max from reps-to-fatigue. JOPERD, 64(1), 88–90 — origin of the Brzycki formula: 1RM = weight × 36 ÷ (37 − reps).
- Additional estimation formulas offered by this calculator: Lander (1985), Lombardi (1989), Mayhew et al. (1992) and O’Conner et al. (1989). All estimates lose accuracy beyond about 10–12 reps.