Calculate your 1RM (one repetition maximum) for any lift using the weight you lifted and reps performed. Also shows training percentages.
This tool estimates your one-repetition maximum (1RM) — the heaviest weight you could lift for a single repetition of an exercise — based on the weight and number of reps you can currently perform. It's widely used in strength training to set training percentages and track progress.
This calculator commonly uses the Epley formula: 1RM = Weight × (1 + Reps ÷ 30). Another common option is the Brzycki formula: 1RM = Weight × (36 ÷ (37 − Reps)). Different formulas can give slightly different estimates, especially at higher rep counts.
Enter the weight you lifted and the number of reps you completed with good form, and the calculator estimates your one-rep max.
Example: If you bench press 100 kg for 5 reps, the Epley formula estimates a 1RM of 100 × (1 + 5/30) ≈ 116.7 kg.
How accurate are 1RM estimation formulas? They provide a useful estimate, generally most accurate for rep ranges under about 10, since formulas become less reliable for very high rep sets, where fatigue and endurance factors play a larger role than pure strength.
Why would I use an estimated 1RM instead of testing it directly? Testing a true 1RM carries higher injury risk and requires more recovery and preparation, so estimating from a comfortable, well-controlled set of reps is often safer and more practical for regular training.
How is 1RM used in training programs? Many strength programs prescribe training weights as a percentage of your 1RM (like 80% for strength work or 60% for hypertrophy work), making an accurate 1RM estimate useful for structuring workouts.
Does 1RM estimation work the same for all exercises? Estimation formulas were primarily developed using compound barbell lifts (like squat, bench, deadlift) and tend to be less reliable for isolation exercises or bodyweight movements.
Should beginners test or estimate their 1RM? Beginners are generally advised to estimate rather than test a true 1RM directly, since proper technique under near-maximal loads takes time to develop, and estimation carries much lower injury risk.