1-Rep Max Calculator
A one-rep max (1RM) calculator estimates the heaviest weight you could lift for a single repetition, based on a lighter weight lifted for multiple reps, using the Epley formula. This avoids the injury risk of testing a true max directly and is the standard way lifters and coaches set training percentages. Results include a percentage table from 50% to 100% of your estimated 1RM for programming sets across a training cycle.
Educational estimate only. Results are not medical, legal, or financial advice. Confirm important decisions with a qualified professional.
How it works
- Enter the weight you lifted and the number of reps you performed.
- The Epley formula estimates your one-rep max.
- Read a percentage table from 50% to 100% of that estimate for programming.
Formula 1RM = weight × (1 + reps/30)
Frequently asked questions
What is a 1-rep max?
It is the maximum weight a lifter can lift for a single complete repetition of an exercise with correct form.
How accurate is the Epley formula?
It is a widely used estimate, most accurate for sets of roughly 10 reps or fewer. Very high rep counts make the estimate less reliable.
Why not just test my true max directly?
Testing a true 1RM carries injury risk, especially without a spotter or coach. Estimating from a sub-maximal set is the safer, standard approach.
What is the percentage table for?
Training programs are often written as a percentage of your 1RM (for example, 5 sets at 75%). The table converts your estimate into those working weights.
Does this work for any exercise?
The formula is exercise-agnostic and commonly applied to squat, bench press, and deadlift, but the same math works for any barbell lift.