One rep max calculator
Estimate the heaviest weight you could lift once.
About this calculator
This one rep max calculator estimates the heaviest weight you could lift for a single repetition, without the risk of testing it. Enter a weight and the number of reps you managed with good form.
It works for the bench press, squat, deadlift and other lifts, and gives a table of training loads from warm-up to near-maximal sets.
How it works
Epley: weight × (1 + reps ÷ 30). Brzycki: weight × 36 ÷ (37 − reps). Lombardi: weight × reps^0.1. The result is the average of the three.
Last reviewed:
Worked example
- Weight lifted: 185
- Weight in: Pounds
- Repetitions: 5
Estimated one-rep max: 213.8 lb (the average of three formulas)
Common questions
Is it safe to test my one rep max?
A true 1RM test is hard on the body and best done with experience, a proper warm-up and a spotter. Estimating it from a set of 3 to 8 reps is safer for most people.
Which 1RM formula is best?
They give similar results for low reps and drift apart above 10. Averaging several formulas, as here, smooths out their differences.
How do I use my 1RM in training?
Programmes often give loads as a percentage of your 1RM, such as 75% for sets of about 10. The training load table shows the weight for each percentage.
The story behind it
Where the idea came from: Boyd Epley, strength coach at the University of Nebraska, published his one-rep max formula in 1985.
Coaches wanted a way to set training loads without asking athletes to lift their absolute maximum. Epley's chart turned any set of several reps into an estimated single-rep max, and Matt Brzycki published a popular alternative in 1993. The formulas remain the standard way to plan strength training.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, not medical advice.
- Spotted a mistake? Tell us and we'll look into it.
After 15 years as a mathematics educator, I built CalculStore to give students, teachers, professionals and anyone working with numbers simple, reliable tools.
Meet the founder