One Rep Max Calculator

Estimate your one-rep max from any set of up to 15 reps, and get training weights by percentage.

Weight lifted	100
Repetitions	5
Unit	lb

Weight lifted

Repetitions

Unit

Estimated one-rep max

114.6 lb

Average of the Epley and Brzycki formulas. Estimates are most reliable for sets of 10 reps or fewer.

Epley: 116.7 lb
Brzycki: 112.5 lb
Lombardi: 117.5 lb
O'Conner: 112.5 lb

Estimate by formula

Epley116.7 lb
Brzycki112.5 lb
Lombardi117.5 lb
O'Conner112.5 lb

Training loads (typical reps at each)

100% · 1 rep114.6 lb
95% · 2 reps108.9 lb
90% · 4 reps103.1 lb
85% · 6 reps97.4 lb
80% · 8 reps91.7 lb
75% · 10 reps85.9 lb
70% · 12 reps80.2 lb
65% · 15 reps74.5 lb
60% · 20 reps68.8 lb

About the One Rep Max Calculator

Testing a true one-rep max is tiring and risky. Formulas estimate it from a heavier set taken close to failure. Epley and Brzycki are the most used; they agree closely between 2 and 10 reps.

The formula

Epley: 1RM = w × (1 + reps ÷ 30); Brzycki: 1RM = w × 36 ÷ (37 − reps)

Worked example

Example: Estimated one-rep max = 129.9 lb

Inputs: Weight lifted: 110; Repetitions: 6; Unit: lb.
Formula: Epley: 1RM = w × (1 + reps ÷ 30); Brzycki: 1RM = w × 36 ÷ (37 − reps)
Result: Estimated one-rep max = 129.9 lb
Epley: 132 lb
Brzycki: 127.7 lb
Lombardi: 131.6 lb

Things to keep in mind

Use a spotter or safety pins for heavy sets.

Questions people ask

Why do the formulas disagree at high reps?

Muscular endurance varies a lot between people; above about 10 reps predictions spread out.

How should I use the percentages?

Strength work is typically 80–90% for 3–6 reps; hypertrophy 65–80% for 8–12.