One Rep Max Calculator
Enter a weight you lifted and how many clean reps you completed. The calculator estimates the most you could lift once and builds a training chart from it.
Result
- Brzycki formula
- 253.1 lb
- Lombardi formula
- 264.3 lb
- O'Conner formula
- 253.1 lb
- Wathan formula
- 262.3 lb
- Average of all formulas
- 259.1 lb
- Epley estimate in kilograms
- 119.1 kg
Training loads based on the Epley estimate
| % of 1RM | Weight (lb) | Typical reps |
|---|---|---|
| 100% | 262.5 | 1 |
| 95% | 249.4 | 2 |
| 90% | 236.3 | 4 |
| 85% | 223.1 | 6 |
| 80% | 210 | 8 |
| 75% | 196.9 | 10 |
| 70% | 183.8 | 12 |
| 65% | 170.6 | 16 |
| 60% | 157.5 | 20 |
| 50% | 131.3 | 30 |
Estimates are most reliable for sets of 2 to 10 reps taken close to failure with good form.
Formula
- Epley: 1RM = w × (1 + r ÷ 30)
- Brzycki: 1RM = w × 36 ÷ (37 − r)
- Lombardi: 1RM = w × r^0.10
- O'Conner: 1RM = w × (1 + 0.025 × r)
- Wathan: 1RM = 100 × w ÷ (48.8 + 53.8 × e^(−0.075 × r))
How the One Rep Max Calculator works
A one rep max is the heaviest weight you can lift once with correct form. Testing it directly is tiring and carries risk, so lifters estimate it from a submaximal set. Each formula fits a curve to the relationship between load and the number of reps possible.
The Epley and Brzycki formulas agree exactly at 10 reps and differ slightly elsewhere. All of them drift as reps climb, because endurance starts to matter more than strength.
Worked example
Lifting 225 lb for 5 reps: Epley gives 225 × (1 + 5 ÷ 30) = 262.5 lb. Brzycki gives 225 × 36 ÷ 32 = 253.1 lb.
Frequently asked questions
Which one rep max formula is most accurate?
Epley and Brzycki are the most widely used and are close for sets under 10 reps. Brzycki tends to read slightly lower for low reps. Taking the average of several formulas is a reasonable approach.
How do I use my one rep max for training?
Programs prescribe loads as a percentage of it. Strength work is usually 80 to 90 percent for 3 to 8 reps, and muscle-building work is 65 to 80 percent for 8 to 15 reps.
Does this work for bench press, squat and deadlift?
Yes. The formulas are not specific to one lift, though individual results vary with the exercise and with training history.
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Calculations run in your browser and nothing you enter is sent to a server. Results are provided for general information. Check critical figures independently before relying on them.