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.

e1RM (Estimated One-Rep Max) — Strength Training Glossary

e1RM (estimated one-rep max) is a 1RM calculated from a submaximal set of any rep count using a 1RM prediction formula or RPE chart.

e1RM lets you track strength progress without testing true maxes. After every heavy set, plug the weight, reps, and RPE into a calculator and you have a continuously-updated estimate of your 1RM. Track the trend rather than any single value.

The most common formulas for computing e1RM are Epley, Brzycki, and the Tuchscherer/Helms RPE chart. Multi-formula averages (like the trimmed mean across all 7 major formulas, used by our main calculator) reduce single-formula bias and produce a more reliable estimate.

e1RM (Estimated One-Rep Max)

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