One Rep Max Calculator

A one rep max is the maximum load you can move through a full range of motion for exactly one repetition with sound technique. It is the universal benchmark for absolute strength and the foundation of percentage-based programming across powerlifting, Olympic lifting, and general strength training. Knowing your 1RM lets coaches prescribe precise training intensities rather than relying on feel alone. For example, if your back squat 1RM is 140 kg, a coach can prescribe 5 sets at 75% (105 kg) with confidence the load is appropriate for your current level.

Most lifters should estimate their 1RM from submaximal sets rather than testing it directly every training block. Repeatedly attempting true maximal lifts places high stress on the nervous system and connective tissue, and the recovery cost often disrupts the training weeks that follow. Estimation from a 3-6 rep set close to failure gives you a reliable enough number for programming purposes without the recovery hit. Reserve true max testing for competition preparation or after a full peaking phase when you have specifically prepared for the attempt.

For most athletes lifting in the 2 to 10 rep range, both Brzycki and Epley produce practical and consistent estimates, and the differences between them are usually within 2-3%. Brzycki tends to be slightly more conservative and is widely considered accurate for heavier, lower-rep sets (3-6 reps). Epley can produce slightly higher estimates, particularly at higher rep counts. When in doubt, use the average of both formulas as your programming anchor and adjust based on how you perform at prescribed percentages over the following weeks.

Accuracy depends strongly on rep quality, proximity to failure, and the exercise being tested. A set of 5 reps taken to true failure will produce a more accurate estimate than a set of 5 reps stopped conservatively. Technical breakdown, fatigue from earlier sets, and individual variation in rep-to-1RM ratios all introduce error. Studies generally report formula accuracy within 5-10% of a tested 1RM for sets of 3-6 reps, but accuracy degrades at higher rep counts. Treat the output as a programming anchor rather than an absolute truth, and recalibrate whenever performance data suggests the estimate is off.

Once you have an estimated 1RM, use it to prescribe working weights as percentages for each session. For example, a hypertrophy block might use 65-75% of 1RM for 3-4 sets of 8-12 reps, while a strength block might use 80-90% for sets of 2-5 reps. Many programs also derive a training max (typically 85-90% of 1RM) to act as a conservative ceiling that keeps prescribed loads manageable as fatigue accumulates across a block. Adjust your estimated 1RM at the start of each new training cycle based on recent performance, not just on a timer.

Yes. Your 1RM is entirely exercise-specific because each lift recruits a different pattern of muscles, levers, and technique demands. Your squat, bench press, deadlift, and overhead press all need to be estimated independently — you cannot extrapolate from one to another. Even variations within the same movement pattern differ: a low-bar squat 1RM will typically be higher than a high-bar squat 1RM for the same athlete. Always record and update each lift's estimate separately, and avoid applying one exercise's percentage table to a different movement.