How to estimate your one-rep max
- Do a hard set of an exercise (for example squat, bench press or deadlift) and note the weight and the number of clean reps.
- Enter the weight and reps and pick kilograms or pounds.
- Read your estimated 1RM, the three formulas behind it, and a table of training weights by percentage, rounded to the nearest plate increment.
How 1RM formulas work
Your one-rep max (1RM) is the most weight you can lift once with good form. Testing it directly is tiring and carries some risk, so lifters estimate it from a heavier set of several reps. This calculator averages three well-known equations: Epley (weight × (1 + reps ÷ 30)), Brzycki (weight × 36 ÷ (37 − reps)) and Lombardi (weight × reps0.10). For a set of 100 kg × 5 they give 116.7, 112.5 and 117.5 kg, so a good estimate is around 115 kg.
The formulas agree closely between 3 and 8 reps and drift apart above 10, because endurance varies so much between people. Results also depend on the exercise: they tend to fit compound lifts better than isolation movements. Programmes such as 5/3/1 or percentage-based strength plans use your 1RM to set working weights, which is what the percentage table is for. The reps column shows the typical number of reps people can do at each percentage.
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Which 1RM formula is the most accurate?
No single formula is best for everyone. Averaging Epley, Brzycki and Lombardi smooths out their biases.
How often should I test my real 1RM?
Many lifters test only every 8–12 weeks, or never, and rely on estimates from regular training sets.
Should beginners test a one-rep max?
It is usually better to estimate it. Beginners gain strength quickly and benefit more from practising technique with moderate weights.