Calculator
One rep max calculator
Enter a weight and how many clean reps you got. You’ll get an estimated one rep max (1RM), a percentage chart for programming, and what you could likely lift for 2 to 10 reps.
Percentages of your 1RM
| % of 1RM | Weight | Typical reps |
|---|---|---|
| 100% | 263 lb | 1 |
| 95% | 249 lb | 2 |
| 90% | 236 lb | 3–4 |
| 85% | 223 lb | 5–6 |
| 80% | 210 lb | 7–8 |
| 75% | 197 lb | 9–10 |
| 70% | 184 lb | 11–12 |
| 65% | 171 lb | 15 |
| 60% | 158 lb | 20 |
| 50% | 131 lb | warm-up |
Estimated rep maxes
Working the formula backwards gives what you could probably lift for a given number of reps. From the example above:
| Reps | Estimated weight |
|---|---|
| 1 | 263 lb |
| 2 | 246 lb |
| 3 | 239 lb |
| 4 | 232 lb |
| 5 | 225 lb |
| 6 | 219 lb |
| 7 | 213 lb |
| 8 | 207 lb |
| 9 | 202 lb |
| 10 | 197 lb |
How the estimate works
Two formulas are widely used, and they agree closely at low reps:
- Epley: 1RM = weight × (1 + reps ÷ 30). The headline number above.
- Brzycki: 1RM = weight × 36 ÷ (37 − reps). Shown underneath for comparison.
Both are estimates. They are closest from sets of about 3 to 6 reps taken near failure with good form, and they drift apart as reps go up. A true one rep max depends on technique, the lift and the day.
Using it safely
You don’t need to test a true max to program by percentages; an estimate from a hard set of 3 to 5 is the usual way to start. If you do attempt a max, warm up, use safety arms or a spotter, and stop when form breaks down.
Track the sets that feed it
The lifting log keeps every set you record and charts your top weight for each lift, so you can see your estimated max move over months.
Log the sets behind your max
Free lifting log with progress charts for every exercise.