One Rep Max Calculator
Calculate your one-repetition maximum (1RM) based on the weight you can lift for multiple reps. Uses four proven formulas and shows training zone percentages.
Number of reps completed with good form (1–30).
Your Results
Estimated One Rep Max
0 kg
Average across all formulas
Formula Comparison
Epley
0
kg
Brzycki
0
kg
Lombardi
0
kg
O'Conner
0
kg
Training Zones
| % of 1RM | Weight | Reps | Training Goal |
|---|
How It Works
Your one-repetition maximum (1RM) is the heaviest weight you can lift for a single rep with proper form. Knowing your 1RM lets you program training percentages for specific goals.
This calculator uses four established formulas — Epley, Brzycki, Lombardi and O'Conner — and averages them for a more reliable estimate. Each formula is most accurate for sets of 2–10 reps.
Use the training zones table to find the right weight for your goal: heavy loads (85–100%) build maximal strength, moderate loads (65–80%) drive hypertrophy, and lighter loads (50–65%) improve muscular endurance.
This calculator provides estimates only. Actual 1RM depends on technique, fatigue, nutrition and other factors. Never attempt a true 1RM without a spotter and proper warm-up.