Bench Press
1RM Calculator.
Enter any weight and rep count to instantly estimate your one-rep max and get every training percentage automatically calculated.
How to Use the 1RM Calculator
Enter the weight you lifted and how many reps you completed. For most accurate results:
- Use a set where you stopped 1-2 reps before failure — don't use a set where you ground out every last rep with terrible form
- Stick to 1-5 reps for highest accuracy — estimates get less reliable above 10 reps
- Use this as an estimate, not gospel — test your actual 1RM every 8-12 weeks
What is a 1RM?
A one-rep max (1RM) is the maximum weight you can lift for one complete repetition with full range of motion and good technique. It's the gold standard for measuring strength and is used to calculate training percentages for periodized programs.
Training Percentages Explained
90-100% (1-3 reps) — Maximal strength. Used for peaking and testing. High neural demand, low volume.
80-90% (3-5 reps) — Strength development. The primary zone for building absolute strength. Core of most powerlifting programs.
70-80% (6-8 reps) — Strength-hypertrophy. Builds both size and strength simultaneously. Most versatile training zone.
60-70% (8-12 reps) — Hypertrophy. Primary muscle-building zone. Lower neural fatigue allows higher volume.
50-60% (12-20 reps) — Muscular endurance. Speed work, technical practice, or conditioning.
Frequently Asked Questions
How accurate is a 1RM calculator?
Most accurate when using 1-5 rep sets. Accuracy decreases above 10 reps as fatigue and endurance become factors. Use a heavy set of 3-5 reps stopped 1-2 shy of failure for best estimates.
Which 1RM formula is most accurate?
Epley and Brzycki are most commonly used and accurate for 1-10 reps. This calculator averages 6 proven formulas for best overall accuracy.
What percentage of 1RM for strength training?
80-95% of 1RM for maximal strength (1-5 reps). 65-80% for hypertrophy (6-12 reps). 50-65% for strength-endurance (12-20 reps).