One-Rep Max (1RM) Calculator
Estimate your maximum single-rep strength from a submaximal set. Most accurate with 3–10 reps performed to near-failure. Use to set training percentages and track progress safely.
Your Lift
Most accurate with 3–10 reps performed to near-failure.
Your Result
Enter the weight and reps from a near-max set.
📋 What Your Result Means
For educational purposes only — not medical advice.
Your estimated 1RM is the foundation of percentage-based training. Update it every 4-8 weeks as you get stronger, and use the table below to program precise loads for any training goal.
| % of 1RM | Rep Range | Training Goal |
|---|---|---|
| 90-100% | 1-3 reps | Maximal strength / peaking |
| 80-90% | 3-6 reps | Strength development |
| 65-80% | 6-12 reps | Hypertrophy (muscle growth) |
| < 65% | 12+ reps | Muscular endurance |
Source: NSCA Essentials of Strength Training and Conditioning, 4th ed. (Haff & Triplett, 2016)
RPE adjustment: If you entered an RPE below 10, the calculator accounts for "reps in reserve" — the reps you could have performed but didn't. This makes the estimate more accurate for sets not taken to muscular failure, which is how most productive training sets are performed.
Accuracy note: 1RM predictions are most reliable when derived from sets of 1-6 reps. Accuracy drops significantly above 10 reps because the relationship between submaximal weight and true max becomes increasingly nonlinear. For best results, use a recent set of 3-5 reps at RPE 8-9.
Brzycki (1993): 1RM = weight × (36 / (37 − reps))
Lander (1985): 1RM = weight / (1.013 − 0.0267123 × reps)
Limitations
Accuracy decreases as rep count increases. Estimates are most reliable between 1–10 reps. Individual variation in strength endurance (fast-twitch vs slow-twitch fibre dominance) affects accuracy. Always approach actual max lifts gradually.
✓ Strong EvidenceWant to learn more? Read our in-depth article: How to Estimate Your One-Rep Max Without Maxing Out →
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