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1RM calculator
Work out your one-rep max, the weight you could lift just once, without having to test it. Enter a weight and the reps you do with it.
Your estimated 1RM
Average of the Epley and Brzycki formulas. Most accurate with sets of 2 to 10 reps.
Weights by percentage
| % of 1RM | Weight | Approx. reps |
|---|---|---|
| 100 % | — | 1 |
| 95 % | — | 2 |
| 90 % | — | 4 |
| 85 % | — | 6 |
| 80 % | — | 8 |
| 75 % | — | 10 |
| 70 % | — | 12 |
| 65 % | — | 15 |
| 60 % | — | 20 |
How it's calculated
- Epley: 1RM = weight × (1 + reps ÷ 30).
- Brzycki: 1RM = weight × 36 ÷ (37 − reps).
- We show the average of both. Above 12 reps the estimate gets less accurate.
What it's for
- Choosing each set's weight from the percentage your routine asks for (for example 5 × 5 at 80%).
- Tracking your strength without max attempts, which carry more risk.
- Comparing exercises and weeks with the same measure.
GymOrbita works out your strength from every set you log and shows how it changes, exercise by exercise. See our routines.
FAQ
Is it safe to test my real 1RM?
A max attempt carries more injury risk, especially without experience or a spotter. The estimate gives you a very useful number without that risk.
Which exercises does it work for?
It works best with compound barbell or machine lifts: bench press, squat, deadlift, overhead press or leg press.
Track your strength in GymOrbita, free
GymOrbita works out your strength from every set you log and shows how it changes, exercise by exercise.