One Rep Max Calculator

One rep max calculators provide estimates that are generally accurate within 5-10% of your actual 1RM. Accuracy depends on the formula used, the number of reps performed, and individual factors like muscle fiber type and training experience. For the most accurate results, use reps in the 3-8 range and compare multiple formulas.

There’s no single “best” formula as accuracy varies by individual and exercise. The Epley formula is most commonly used and works well for general purposes. The Brzycki formula tends to be more accurate for lower rep ranges (1-5), while the Wathan formula is considered one of the most accurate across all rep ranges. Our calculator shows results from multiple formulas so you can compare.

For most lifters, testing your actual 1RM every 8-12 weeks is sufficient. Frequent max testing can increase injury risk and interfere with training progress. Between tests, use calculated estimates like those from this calculator to track strength gains. Advanced lifters might test specific lifts more frequently during peaking phases.

1RM calculators work best for compound exercises like squats, bench presses, deadlifts, and overhead presses. They’re less accurate for isolation exercises, bodyweight exercises, or exercises where technique significantly impacts performance. For exercises like pull-ups or dips, other methods like adding weight may be more appropriate for determining max strength.

To improve your 1RM, focus on progressive overload in your training, ensure adequate recovery and nutrition, and include both heavy low-rep work and moderate higher-rep work in your program. Specific techniques like periodization, varying exercise selection, and addressing weak points in your lifts can also help increase your maximal strength over time.