Estimate your one rep max (1RM) using Epley, Brzycki or Lombardi formula with training percentages.
A one-rep max (1RM) calculator estimates the maximum weight you could lift for a single repetition of a lift, based on a submaximal set you have actually performed. Testing a true 1RM is risky and physically demanding; estimating from a 3RM or 5RM is safer and accurate enough for programming purposes.
Knowing your 1RM lets you train at precise percentages of maximum — the foundation of all evidence-based strength programs. A typical hypertrophy block uses 65–80% 1RM, strength work uses 80–90%, and power/peak work uses 90%+.
1RM = W \times \frac{36}{37 - r} \quad (\text{Brzycki})
Inputs: You squatted 100 kg for 5 strong reps with one rep left in the tank
For 1–5 reps, Brzycki tends to slightly underestimate and Epley slightly overestimates. The average of the two is usually closest to a real 1RM. For lifts above 10 reps, all formulas lose accuracy because endurance starts to dominate over strength.
Estimate. True 1RM testing is high injury risk, requires extensive warm-up and a spotter, and your nervous system needs 5–7 days to recover afterwards. Estimated 1RMs from 3–5 rep sets are accurate within 2–5% and are essentially free to compute. Re-estimate every 6–8 weeks as you progress.
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