About this calculator
Enter the weight and reps from a hard set. The calculator averages three common formulas and lists training weights as percentages of your 1RM.
How to use it
- Enter the weight lifted.
- Enter the reps completed.
- Read your estimated 1RM and training weights.
The formula
Epley: 1RM = weight × (1 + reps ÷ 30); Brzycki: 1RM = weight × 36 ÷ (37 − reps)
- weight
- what you lifted
- reps
- how many times, to near failure
Worked example
80 kg for 8 reps
- Epley: 101.3 kg; Brzycki: 99.3 kg; Lombardi: 98.5 kg.
- Average estimate: 99.7 kg.
- Training at 75% means about 74.8 kg for sets of 10.
What the result means
Estimates are most accurate from sets of 2 to 10 reps.
Assumptions
- The set was close to failure with good form.
Limitations
- Different lifts and people vary; treat it as a guide.
Frequently asked questions
How do I calculate my 1RM?
Lift a weight for as many good reps as you can, then use a formula such as Epley.
Should I test a true 1RM?
Only with a proper warm-up and a spotter, and not often.
What percentage for muscle growth?
Commonly 65% to 85% of 1RM for 6 to 15 reps.
Not medical advice. This calculator is a general screening tool and cannot diagnose any condition. Results are estimates. Please talk to a doctor or a qualified health professional about your health and before making changes to diet, exercise or treatment.
Last reviewed on 1 October 2026. Found a mistake? Tell us.