Estimate your one rep max from any working set using Epley, Brzycki, and Lombardi formulas.
Estimated one-rep max using two common formulas. Epley: 1RM = weight × (1 + reps/30). Brzycki: 1RM = weight × 36 / (37 − reps). Use the calculator above for personalized numbers:
| Working set | Epley 1RM | Brzycki 1RM | % of 1RM |
|---|---|---|---|
| 100 lb × 5 reps | 115.0 lb | 112.5 lb | ~87% |
| 135 lb × 5 reps | 155.3 lb | 152.0 lb | ~87% |
| 185 lb × 3 reps | 205.8 lb | 201.5 lb | ~92% |
| 225 lb × 1 rep | 225 lb | 225 lb | 100% |
| 95 lb × 10 reps | 127.5 lb | 120.8 lb | ~75% |
| 200 lb × 8 reps | 266.7 lb | 253.3 lb | ~80% |
Both formulas are most accurate at 1-10 reps; estimates diverge above 10 reps. Always warm up properly and avoid testing true 1RM without a spotter. References: Epley (1985); Brzycki (1993).
Input weight and reps to estimate your 1RM
The Epley formula is the most commonly used 1RM estimator: 1RM = weight × (1 + reps/30). These formulas are most accurate for 1-10 reps. Beyond 10 reps, accuracy decreases due to endurance factors.
Always warm up properly and use a spotter when attempting a true 1RM. The estimated value is a safe starting point for programming.
Type the weight you lifted and the number of clean reps you completed. Best results come from sets of 1-10 reps.
Using Epley, Brzycki, Lombardi, and OConner formulas, we compute an estimated 1RM. The calculator shows all four estimates so you can pick the most conservative.
Get a chart of 50-100% 1RM weights for hypertrophy (65-75%), strength (80-90%), and power (85-95%) training zones.
For related calculations, try our BMI calculator.
Cross-checked against authoritative formulas (IRS, NIST, ACSM) and updated for 2025/2026 tax years and rates.
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Estimates only. Calculator results are for educational and planning purposes — not professional advice. For binding decisions on taxes, investments, health, or legal matters, consult a qualified professional.