📊 One-Rep Max Calculator
Estimate your 1-rep max from any weight and rep count using three proven formulas.
Your 1-Rep Max Estimates
Brzycki 1–6 reps
Conservative, most accurate
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Epley 3–5 reps
Good for low rep ranges
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Lander All ranges
Works across rep ranges
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⭐ Average
Most reliable single estimate
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How the one-rep max formulas work
A one-rep max (1RM) is the most weight you can lift for a single clean repetition. Rather than grinding out a true max attempt every time — which is fatiguing and carries injury risk — you can estimate it from a lighter set taken close to failure. This calculator runs three of the most widely used equations and averages them:
- Brzycki: weight × (36 / (37 − reps)). Tends to be conservative and is most reliable at 1–6 reps.
- Epley: weight × (1 + reps / 30). A long-standing standard that holds up well at low-to-moderate reps.
- Lander: (100 × weight) / (101.3 − 2.67123 × reps). Useful across a wider range of reps.
Getting the most accurate estimate
Use a set you took within a rep or two of failure, ideally in the 3–6 rep range. The further past ~10 reps you go, the more the estimate drifts, because high-rep performance depends heavily on conditioning and pain tolerance rather than pure maximal strength. Once you have a number, you can use it to set training percentages — then see how it stacks up on the strength standards calculator.