One rep max calculator
Estimate 1RM from a set completed close to repetition failure.
Formula
1RM = load / (1.0278 − 0.0278 × reps)
Load lifted: 135 lb · Estimated 1RM in kg ≈ (135 lb × 0.45359237 kg/lb)÷(1.0278-0.0278×(5)) · Estimated 1RM in lb ≈ (68.89623082)÷0.45359237
How to use
- Enter the load lifted.
- Enter 1–10 completed repetitions.
- Read the estimate in kg and lb.
Examples
- 80 kg for 5 reps gives an estimated 1RM of 90.01 kg.
Frequently asked questions
Which equation is used?
Brzycki with coefficients 1.0278 and 0.0278, as reported by Armes and colleagues.
Is this a guaranteed maximum?
No. Exercise, technique, fatigue and proximity to failure affect the estimate.
Can I enter more than 10 reps?
This tool limits input to 10 because high-repetition estimates are less dependable.
Sources
Updated: