One Rep Max Calculator
Estimate your 1RM for any lift using a weight you've already moved. Get your full training percentage breakdown instantly.
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What is a One Rep Max (1RM)?
Your one rep max is the maximum amount of weight you can lift for a single repetition with good form. It's the standard way to measure absolute strength in resistance training, and it's used to program training loads for strength, hypertrophy, and power.
Testing your true 1RM carries injury risk — especially for beginners. That's why 1RM estimation formulas exist: you lift a submaximal weight for multiple reps, and the formula predicts your maximum. These estimates are accurate to within about 5% for reps under 10.
How to use your 1RM for training
Once you have your estimated 1RM, you can set training loads as a percentage of that number. Different percentages target different training goals:
- 50–60%: Warm-up, technique work, active recovery
- 60–70%: Muscular endurance (15+ reps)
- 70–80%: Hypertrophy / muscle building (8–12 reps)
- 80–90%: Strength development (3–6 reps)
- 90–100%: Maximum strength, competition lifts (1–3 reps)
The formulas explained
Epley: weight × (1 + reps / 30) — most widely used, tends to be accurate for moderate rep ranges
Brzycki: weight × 36 / (37 − reps) — accurate for lower rep ranges (1–10)
Lander: (100 × weight) / (101.3 − 2.67123 × reps) — validated in research studies
Lombardi: weight × reps^0.10 — tends to give higher estimates, good for higher rep ranges
Average: Mean of all four formulas — reduces outlier bias
For best accuracy, use a weight you can lift for 3–8 reps with good form. Estimates become less reliable above 10 reps.