One-Rep Max Calculator
Estimate your one-rep max (1RM) from a lighter set — compare seven recognised formulas, see the exact weight and plate loading for every training percentage, and check your relative strength against illustrative strength standards.
Not coaching advice. This 1RM calculator gives an estimate only, based on recognised strength-estimation formulas — it is not personal coaching or medical advice. Attempting a true one-rep max carries injury risk; always warm up properly and use a spotter or safety equipment. Relative-strength standards are illustrative rules of thumb, not a validated normative dataset.
Enter a weight and rep count
Your estimated one-rep max and training percentage table appear here as you type.
How your 1RM is estimated
Your one-rep max is the heaviest weight you could lift for a single rep with good form. Rather than testing it directly — which carries injury risk without a spotter and a proper warm-up — this calculator estimates it from a set you've already done. The headline figure is the average of two widely used formulas: Epley (1RM = weight × (1 + reps ÷ 30)) and Brzycki (1RM = weight × 36 ÷ (37 − reps)). The %1RM table below uses the standard strength-training chart (Baechle & Earle, NSCA) to show roughly how many reps you'd typically manage at each percentage of your max — useful for planning training blocks.