One Rep Max Calculator
Estimate your 1RM from any set
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About this calculator
Instead of testing a risky single, lift a weight for 2–10 reps and estimate your maximum. The result averages the Epley, Brzycki, Lander and Lombardi formulas and shows training percentages.
The formula
Epley: 1RM = weight × (1 + reps ÷ 30) | Brzycki: weight × 36 ÷ (37 − reps)
Worked example100 kg for 5 reps → Epley 116.7 kg.
Frequently asked questions
How many reps give the best estimate?
Sets of 3–8 reps are most accurate. Above 12 reps the estimate drifts.
Is it safe to test a true 1RM?
Only with warm-up, good technique and a spotter.
What are the percentages for?
Use them to plan working sets, e.g. 5 × 5 at 80%.
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