One Rep Max Calculator (Epley and Brzycki)
Enter the weight you lifted and how many reps you completed to estimate the most you could lift once.
Updated
Report a problem
Formula
- Epley:
1RM = weight × (1 + reps ÷ 30) - Brzycki:
1RM = weight × 36 ÷ (37 − reps)
Worked example
100 for 5 reps: Epley gives 100 × (1 + 5 ÷ 30) = 116.7; Brzycki gives 100 × 36 ÷ 32 = 112.5. The average is 114.6.
Frequently asked questions
What is a one-rep max?
Your one-rep max (1RM) is the heaviest weight you can lift for a single repetition with good form. Estimating it from a lighter set avoids testing it directly.
What are the Epley and Brzycki formulas?
Epley: 1RM = weight × (1 + reps ÷ 30). Brzycki: 1RM = weight × 36 ÷ (37 − reps). For 100 × 5 they give 116.7 and 112.5.
Why is the number of reps limited to 12?
Estimates are most reliable for sets of about 10 reps or fewer. Brzycki also breaks down near 37 reps, so higher-rep sets are not supported.
Which formula should I use?
Neither is always right. They agree closely around 10 reps (60 × 10 gives 80 in both) and differ more at low reps, so the average is a reasonable middle estimate.