Calculator
One rep max calculator
Enter the weight you lifted and how many reps you got. Best accuracy from sets of 2–6 reps.
Training percentages
| % of 1RM | Weight (kg) | Reps you can do |
|---|---|---|
| 100 % | 92.5 | 1 |
| 95 % | 87.5 | 2 |
| 90 % | 82.5 | 3–4 |
| 85 % | 77.5 | 5–6 |
| 80 % | 72.5 | 7–8 |
| 75 % | 70 | 9–10 |
| 70 % | 65 | 11–12 |
| 65 % | 60 | 13–15 |
| 60 % | 55 | 16–20 |
| 55 % | 50 | 20+ |
| 50 % | 45 | 25+ |
The formulas
- Epley: 1RM = w × (1 + r ÷ 30)
- Brzycki: 1RM = w × 36 ÷ (37 − r)
- Lombardi: 1RM = w × r0.10
- O'Conner: 1RM = w × (1 + 0.025 × r)
Use the estimate to set percentages in a program, not to attempt a max. If you are new to lifting, run the generator with the strength goal: it prescribes 4–6 rep sets at RPE 8, which is where these formulas are most accurate.
Frequently asked questions
How accurate is a one-rep max calculator?
Within about 5 % for sets of 2–6 reps. Accuracy drops as reps go up; sets above 10 reps say more about endurance than max strength.
Which formula should I use?
Epley and Brzycki are the most used and agree closely under 10 reps. We show the average of four formulas as the headline number.
How do I use the percentage table?
Pick the rep range your program asks for and load the matching percentage. For strength work 85–95 %, for muscle 65–80 %, for warm-ups 40–60 %.
Should I ever test a true 1RM?
Only if you compete. For programming, an estimate from a 3–5 rep set is safer and good enough.