One rep max calculator
Estimate your one rep max from a recent set, then see the weight for every percentage and rep count.
From a set worth 5 reps to failure, rounded to 2.5 kg.
| Percent | Weight | Reps to failure |
|---|---|---|
| 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 | 12+ |
| 65% | 75 kg | 12+ |
| 60% | 70 kg | 12+ |
| 55% | 65 kg | 12+ |
| 50% | 57.5 kg | 12+ |
How the estimate works
Enter a recent hard set and the calculator works out the heaviest single you could likely lift, using the Epley formula: one rep max = weight x (1 + reps / 30). If the set was not to failure, pick how hard it felt and the reps you had left are added before the formula runs.
Using the tables
- Percent of max: the load for each percentage most programs prescribe, with the reps to failure that load allows. Work sets usually stop a rep or two short of that number.
- Rep maxes: the most you could likely lift for 1 to 12 reps. Handy for picking a weight for a set of 5 or 8 without guessing.
Weights are rounded to 2.5 kg or 5 lb, the smallest jump most gyms can load.
Getting a good number
- Use a set of 3 to 8 reps taken close to failure with clean form.
- Use a set from this week, not your best ever.
- Each lift has its own max. A bench number says little about your squat.
Questions
How accurate is a one rep max calculator?
Within a few percent for most lifters when the set is 3 to 8 hard reps. The further a set is from a true max, the more the estimate depends on how well you hold up over many reps, which varies from person to person and lift to lift.
Which formula does this use?
Epley: weight times one plus reps over thirty. A single to failure counts as the max itself, because plain Epley would add about 3% to it. It is the same formula Zurge uses for estimated maxes in the app.
Why does RPE change the estimate?
A set left with reps in the tank was not your limit for that weight. At RPE 8 you had about two more, so 100 kg for 5 at RPE 8 is scored like 7 reps to failure.
Why does a set of 15 give a warning?
Past about 12 reps to failure, endurance starts to matter as much as strength, and Epley overstates the max. A heavier set of 3 to 8 gives a better number.
Should I test my true one rep max?
You do not need to for most training. Programs written in percentages work fine off an estimate, and an estimate from a recent hard set is safer to get than a max attempt. If you do test, warm up well and use a spotter or safety arms.