How to estimate your one rep max
Testing a true one rep max is tiring and carries some risk. These formulas estimate it from a set you can do safely, and they're most accurate from 2 to 10 reps.
Example: bench pressing 225 lb for 5 reps gives 262.5 lb with Epley, 253.1 lb with Brzycki and 264.3 lb with Lombardi, an average of about 260 lb. Training at 80% for sets of 8 means about 210 lb.
Using percentages to train
- Strength: 85% to 95% for 1 to 5 reps.
- Muscle size: 65% to 85% for 6 to 12 reps.
- Endurance: under 65% for 15 or more reps.
Use a spotter or safety bars for heavy sets, and re-test every few weeks as you get stronger. Formulas tend to underestimate for lower-body lifts like the squat and deadlift in trained lifters. Track calories burned in the gym with the calories burned calculator.
Frequently asked questions
Which one rep max formula is most accurate?
Studies find Epley and Brzycki among the most accurate for under 10 reps. They agree closely at 5 reps or fewer; averaging several formulas smooths out the differences.
How many reps should I use to estimate 1RM?
Sets of 3 to 6 reps give the best estimates. Beyond 10 reps, endurance plays a bigger role and the estimate becomes unreliable.
Is it safe to test a one rep max?
For experienced lifters with good form, a spotter and a proper warm-up, yes. Beginners are better off estimating from a moderate set.
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