💪 One Rep Max (1RM) Calculator
Estimate your maximum lift (1RM) from a submaximal weight and reps using 7 proven formulas.
Your Lift
Estimated 1RM
0
What is the One Rep Max?
The 1 Rep Max (1RM) is the maximum weight you can lift for a single repetition of an exercise with perfect form. It's the gold standard for measuring strength in powerlifting and weightlifting.
Why Calculate Rather Than Test?
Maximal testing is physically demanding and carries injury risk. Submaximal testing (lifting a known weight for multiple reps) provides a safe, reliable estimate. The formulas are most accurate when using 2–10 repetitions; accuracy decreases above 10 reps.
What percentage of 1RM should I train at? +
Training zones by % 1RM: 90–100% = max strength (1–3 reps), 80–89% = strength (3–5 reps), 67–79% = hypertrophy (6–12 reps), 50–66% = endurance (15+ reps). Most hypertrophy programs use 70–80% for sets of 8–12.