Calculate your 1RM
1RM (one rep max) is the maximum weight you can lift once in a given exercise. It is one of the most important measurements in strength training, used to determine training intensity and load. Our calculator uses the Brzycki formula, one of the most recognised methods for estimating 1RM.
The Brzycki formula
The Brzycki formula calculates 1RM as: weight / (1.0278 - 0.0278 x reps). The formula is most accurate for 1-10 reps. For more reps, the estimate becomes less accurate. For example: if you lift 80 kg for 5 reps, your estimated 1RM is about 90 kg.
Training percentages
From your 1RM you can calculate training loads: 90% of 1RM for heavy strength training (1-3 reps), 80% for strength and hypertrophy (4-6 reps), 70% for hypertrophy (8-12 reps), and 60% for endurance (15-20 reps). These percentages are guidelines and may vary individually.
Safety when testing 1RM
It is recommended to test 1RM with a spotter and after thorough warm-up. Alternatively, use this calculator with a submaximal lift (3-5 reps) to estimate your 1RM safely. Avoid testing 1RM too often โ every 4-8 weeks is sufficient to measure progress.