One Rep Max Calculator

How to Estimate Your One-Rep Max

Your one-rep max (1RM) is the heaviest weight you can lift for exactly one repetition. Testing it directly is risky, so formulas estimate it from submaximal lifts.

Two popular formulas

Epley: 1RM = Weight × (1 + Reps ÷ 30)

Brzycki: 1RM = Weight ÷ (1.0278 − 0.0278 × Reps)

This calculator averages both for a balanced estimate.

Step-by-step

1. Enter the weight you lifted (in pounds).
2. Enter how many reps you performed at that weight.
3. The calculator outputs an estimated 1RM.

Worked example

You bench-pressed 185 lbs for 5 reps. Epley: 185 × (1 + 5/30) = 215.8. Brzycki: 185 ÷ (1.0278 − 0.139) = 211.2. Average ≈ 213.5 lbs.

Training percentages

Use your 1RM to plan training loads: 65–75% for hypertrophy, 80–90% for strength, 90–95% for peaking. Most programs are built around percentage of 1RM.