What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift once with good form. Many strength programs prescribe loads as a percentage of 1RM, so knowing it helps you train with the right weight.
Formulas we use
We show the average of both. Both are very accurate up to about 10 reps; above that the error grows quickly, so use heavy sets of 3 to 8 reps to estimate your max.
How to use the percentage chart
The chart shows what weight to use for each percentage of your 1RM and how many reps you can typically do with it. Max-strength work usually sits at 85–95%, and hypertrophy work at 65–80%.
Safety tips
- Warm up thoroughly before heavy sets.
- Use safety bars or a spotter on bench press and squat.
- Stop the set when your form breaks down, even if you have a rep left.
Frequently asked questions
Is it safe to test my true 1RM?
For experienced lifters with solid technique, yes, with a proper warm-up and safety equipment. For beginners, estimating it with this calculator is safer.
Which 1RM formula is the most accurate?
Epley and Brzycki give nearly identical results between 2 and 10 reps, which is why we show their average.
Does it work for any exercise?
It works best for compound barbell lifts like squat, bench press, deadlift and overhead press. It's less reliable for machines and isolation exercises.
How often should I recalculate my 1RM?
Every 4–8 weeks, or at the end of each training block, to adjust your loads to your progress.
Results are estimates for general information only and are not a substitute for advice from a doctor, registered dietitian or qualified coach.