How accurate are 1RM calculators?

1RM calculators are generally accurate within 5-10% when used with rep ranges under 10. The accuracy depends on factors like training experience, muscle fiber composition, and the specific formula used. Our calculator uses 7 different formulas to give you the most comprehensive estimate.

Which 1RM formula is most accurate?

The Epley formula is most widely used and accurate for most people, especially with rep ranges of 2-10. However, different formulas work better for different individuals. Brzycki tends to be conservative, while Lombardi works well for powerlifters. Our calculator shows all 7 formulas so you can compare.

Can I use this for any exercise?

Yes, you can use 1RM calculators for any compound exercise like bench press, squat, deadlift, overhead press, and rows. The formulas are based on general strength principles that apply across exercises, though they're most accurate for compound movements.

What rep range should I use for the most accurate calculation?

For best accuracy, use rep ranges between 2-10 reps. The sweet spot is 3-8 reps where most formulas perform optimally. Avoid using very high rep ranges (15+) as the formulas become less reliable due to muscular endurance factors.

How often should I recalculate my 1RM?

Recalculate your 1RM every 4-6 weeks or whenever you notice significant strength gains. For beginners, monthly calculations work well. Advanced lifters might recalculate every 6-8 weeks. Always use recent max effort sets for the most accurate results.

Training Max (TM) — Strength Training Glossary

Training Max (TM)

Training Max is a working percentage (typically 85-90%) of true 1RM used as the base for percentage-based training prescriptions.

The Training Max is the central concept in Jim Wendler's 5/3/1 program and is widely used in other periodized templates. By basing all working percentages on a TM rather than true 1RM, programs build in a buffer that absorbs daily strength fluctuations and reduces overshoot risk.

Most programs use TM = 90% of 1RM for advanced lifters and TM = 85% of 1RM for novices, intermediates, or anyone returning from a layoff. When 1RM tests are infrequent (or skipped entirely), the TM is updated by adding small fixed increments (typically 5 lb upper / 10 lb lower) at the end of each successful training cycle.

Training Max (TM)

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