How to use it
- Step 1Enter the weight you lifted.
- Step 2Enter how many clean reps you completed (1 to 12).
- Step 3Read your estimated 1RM and a load chart from 60% to 100%.
The formulas
- Epley: weight × (1 + reps ÷ 30)
- Brzycki: weight × 36 ÷ (37 − reps)
- Lombardi: weight × reps^0.10 (shown for comparison)
The headline number averages Epley and Brzycki. Worked example: 185 lb for 5 reps: Epley 216, Brzycki 208, average 212 lb.
Accuracy
Estimates are most accurate from sets of 10 reps or fewer, taken close to failure with good form. Test true maxes only with a spotter or safety bars.
Prefer a chart? See 1RM charts by weight: precomputed tables for common inputs.
More fitness
Common questions
How accurate is a 1RM calculator?
From sets of 3 to 6 reps, estimates are often within about 5% of a tested max. Accuracy drops with higher reps.
What percentage of 1RM should I train at?
Strength work often uses 75% to 90%, and muscle-building work 60% to 80%, depending on reps.
Should I test my real 1RM?
It's not needed for most people. Estimates are safer and good enough to plan training.
Does strength training help with weight loss on a GLP-1?
It helps protect muscle while you lose weight, along with enough protein.