One Rep Max Calculator: Estimate Your Max Without Testing It
Testing a true one-rep max is risky and tiring. The Epley formula estimates it from a safer set, so you can plan training loads without maxing out.
What is the One Rep Max Calculator?
Enter a weight you lifted and how many reps you managed, and the tool estimates your one-rep max with the Epley formula: weight times one plus reps divided by thirty. This is an estimate for programming training loads, not a test — never attempt a true one-rep max without proper coaching and safety.
How to use it
- Enter the weight you lifted.
- Enter how many reps you completed.
- Click Estimate 1RM for the Epley estimate.
Worked example
Lifting 100 for 5 reps gives an estimated one-rep max of 116.67, since 100 times (1 + 5/30) equals 116.67.
How accurate is the Epley estimate?
Reasonably close for sets of 10 reps or fewer. Beyond that, fatigue makes the estimate less reliable.
Frequently asked questions
Should I try my estimated max?
Only with proper coaching, a spotter, and safe equipment. The estimate is for planning, not a challenge.
Does the unit matter?
No. The result is in whatever unit you entered — kilograms in, kilograms out.