Free Tool
1RM Calculator
Enter the weight you lifted and how many reps you completed. We'll show you what every major 1RM formula predicts, side-by-side, so you can pick the most accurate one for your rep range.
New to a one-rep max (1RM)? Read the plain-English definition →
Your set
Estimated 1RM
All 7 formulas compared. The recommended formula for your rep count is highlighted.
| Method | 1RM |
|---|---|
Epley | 262.5 lb |
BrzyckiBest fit | 253.1 lb |
Lombardi | 264.3 lb |
Lander | 255.8 lb |
O'Conner | 253.1 lb |
Mayhew | 267.8 lb |
Wathen | 262.3 lb |
% of 1RM chart
Working sets at common training percentages, based on Epley estimate of 263 lb.
| Target reps | % of 1RM | Weight (lb) |
|---|---|---|
| 1 | 100% | 262.5 |
| 2 | 95% | 249.4 |
| 3 | 93% | 244.1 |
| 4 | 90% | 236.3 |
| 5 | 87% | 228.4 |
| 6 | 85% | 223.1 |
| 8 | 80% | 210 |
| 10 | 75% | 196.9 |
| 12 | 70% | 183.8 |
| 15 | 65% | 170.6 |
Track your 1RM progress over time
Zealova logs every set, calculates an updated 1RM after each workout, and adjusts your next plan around the new number.
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Methodology + Sources
- Epley B (1985). Poundage Chart. Boyd Epley Workout, Lincoln, NE.
- Brzycki M (1993). Strength testing: predicting a one-rep max. JOPERD 64(1).
- Lombardi VP (1989). Beginning Weight Training: The Safe and Effective Way.
- Wathen D (1994). Load assignment. NSCA Essentials of Strength Training and Conditioning.
- Mayhew JL et al. (1992). Relative muscular endurance performance as a predictor of bench press strength. JASSR 6(4).
Last updated: 2026-05-14
Built by Sai, founder of Zealova. Not a neutral third party. Calculator results are estimates. For medical decisions, consult a qualified professional.
Frequently asked questions
Which 1RM formula is most accurate?+
It depends on the rep range. Brzycki is most accurate for low reps (2-5). Epley works well for moderate reps (5-10). Above 10 reps, all formulas lose accuracy because muscular endurance becomes a larger factor than maximal strength. We highlight the recommended formula for your rep count.
How many reps should I use for the most accurate estimate?+
Between 3 and 6 reps gives the most accurate prediction. Above 10 reps, error rates climb significantly. For your competition lifts, performing a true 1RM attempt is still the gold standard.
Can I use this for all exercises?+
Yes, but accuracy varies. The formulas were originally validated on bench press and similar barbell lifts. They work reasonably well for squat, deadlift, overhead press, and most compound lifts. Single-joint and machine exercises produce less reliable estimates.
Why do different formulas give different results?+
Each formula was developed from a different study population (often college athletes) and a specific exercise. The differences across formulas reflect those original samples, not which one is "right" in an absolute sense. Looking at the range across formulas gives you a confidence interval rather than a single point estimate.
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