One-rep max calculator

Estimate the most you could lift for one rep from a lighter set. This avoids testing a risky heavy single.

Enter a recent set to see your estimate.

How it works

The calculator uses the Epley formula: one-rep max = weight x (1 + reps / 30). Lift Log uses the same formula to spot personal records. It is most accurate for sets of 2 to 10 reps and less reliable above 12.

How to use the percentages

Around 70 to 75 percent suits sets of 10 to 12 reps.
Around 80 to 85 percent suits sets of 6 to 8 reps.
Beginners should stay in the 10 to 12 range and not test a real one-rep max.

Next: how much weight should a beginner lift?

Track it in Lift Log

Log your sets, keep a weekly streak and see your progress in one place. Lift Log is a private gym log that works offline and syncs to your phone.

Open the app