One Rep Max (1RM) Calculator

This calculator estimates your one-rep max, or 1RM, the heaviest weight you could lift once for a given exercise, from a set you have actually done, so you never have to risk a true maximal lift to know your number. Your 1RM is the reference point for serious strength training: programmes prescribe loads as a percentage of it, so knowing your max for the squat, bench press, deadlift and other lifts lets you train at the right intensity. The problem is that actually testing a true one-rep max is risky, tiring and best done with a spotter, which is where prediction formulas come in. By taking a weight you lifted for several reps to near failure, well-validated equations estimate the single-rep maximum with good accuracy, particularly in the 1 to 10 rep range. You enter the weight you lifted and the number of clean reps you managed, and the calculator returns your estimated 1RM using the popular Epley formula, a cross-check using the Brzycki formula, and a set of training loads at 95, 90, 85 and 80 percent of your max, which correspond to common rep ranges from heavy singles and triples through to hypertrophy work. Use it to set working weights, to track strength gains over time, and to plan a programme without maxing out. Accuracy is best when the reps are genuinely hard and in the lower range; very high-rep sets overestimate the max. Always warm up, use good form and a spotter for heavy work, and treat the result as a training guide rather than a guarantee of what you can lift on the day.

Most accurate in the 1-10 rep range; high-rep sets overestimate. Warm up, use good form and a spotter for heavy lifts. A training guide.