1RM Calculator (one-rep max)
Enter the weight you lifted and how many clean reps you got: the calculator estimates your one-rep max (1RM) and gives you the load to use at each percentage of it.
Calculate your 1RM
Your estimated 1RM
116.7 kg
Above 10 reps the estimate gets less accurate: for a reliable number, use a set of 3 to 10 reps.
| % 1RM | Load | Approx. reps |
|---|---|---|
| 100% | 117.5 kg | 1 |
| 95% | 110 kg | 2 |
| 90% | 105 kg | 3 |
| 85% | 100 kg | 5 |
| 80% | 92.5 kg | 8 |
| 75% | 87.5 kg | 10 |
| 70% | 82.5 kg | 13 |
| 65% | 75 kg | 16 |
| 60% | 70 kg | 20 |
Loads are rounded to 2.5 kg or 5 lb. The reps are what the same formula predicts at that load: a guide, not a target you have to hit.
How the calculation works
The calculator uses the Epley formula, one of the most common ways to estimate your max without having to test it:
1RM = weight × (1 + reps ÷ 30)
If you get 5 reps with 225 lb, your estimated 1RM is 225 × (1 + 5 ÷ 30) = 262.5 lb; with 100 kg it comes to about 116.7 kg. The table under the result applies each percentage to that number: it's the usual way to pick the weights for a program (for example 4 sets of 6 at 80%).
When the estimate is reliable
- Use a real set: clean reps with good form, close to failure but without your technique breaking down.
- Stay between 3 and 10 reps: in longer sets endurance starts to matter and the estimate drifts.
- One lift at a time: your bench press max tells you nothing about your squat. Work it out for every exercise you want to program.
- It's an estimate: two people with the same 1RM can get a different number of reps with the same weight. Use it to find your bearings, not as gospel.
Why estimate it instead of testing it
Testing your true max takes a long warm-up, a spotter and solid technique under the heaviest weight you have ever lifted. For most people who train, the risk isn't worth the number: an estimate from a set of 3 to 8 reps is plenty to program your loads and see whether you're getting stronger.