AstraCalculator

One Rep Max Calculator

Enter a set you actually completed. This estimates the single heaviest rep you could manage, then gives the training weights that follow from it.

lb
reps

How the math works

Epley: 1RM = weight x (1 + reps / 30). Brzycki: 1RM = weight x 36 / (37 - reps). The two disagree by a few percent, so this averages them. Training percentages are taken from that average and rounded to the nearest 5 lb.

Common questions

How do I calculate my one rep max without testing it?
Take a set you finished with maybe one rep left in you, and enter the weight and reps. A set of 3 to 6 reps gives the most reliable estimate, and it avoids the injury risk of a true max attempt.
Epley or Brzycki, which is right?
Neither, exactly. Brzycki tends to read lower at higher reps and Epley higher. Below 10 reps they land within a few percent of each other, which is why the average above is a reasonable working number.
What percentage should I train at?
Broadly, 85 percent and up for strength, 67 to 85 for muscle growth, and below 67 for endurance. Most programs spend the bulk of their volume between 70 and 85 percent, not at the top.

People also work out