One rep max calculator
Enter the weight and the reps of a hard set. You get your estimated one-rep max (1RM), a percent chart, a rep table and a warm-up.
Use a set you did to failure or within 1 rep of failure, with good form.
Estimated one-rep max
115 kg
Epley: 117.5 kg · Brzycki: 112.5 kg
| Percent | Weight |
|---|---|
| 100% | 115 kg |
| 95% | 110 kg |
| 90% | 102.5 kg |
| 85% | 97.5 kg |
| 80% | 92.5 kg |
| 75% | 85 kg |
| 70% | 80 kg |
| 65% | 75 kg |
| 60% | 70 kg |
| 55% | 62.5 kg |
| 50% | 57.5 kg |
| Reps | Weight |
|---|---|
| 1 | 115 kg |
| 2 | 110 kg |
| 3 | 105 kg |
| 4 | 102.5 kg |
| 5 | 100 kg |
| 6 | 97.5 kg |
| 7 | 95 kg |
| 8 | 92.5 kg |
| 9 | 87.5 kg |
| 10 | 85 kg |
| 11 | 82.5 kg |
| 12 | 80 kg |
| Set | Weight | Reps |
|---|---|---|
| 1 (40%) | 45 kg | 8 |
| 2 (55%) | 62.5 kg | 5 |
| 3 (70%) | 80 kg | 3 |
| 4 (80%) | 92.5 kg | 2 |
| 5 (90%) | 102.5 kg | 1 |
How it works
Your one-rep max is the heaviest weight you can lift once with good form. The calculator estimates it from a set of more reps with two public formulas:
- Epley: 1RM = weight × (1 + reps ÷ 30)
- Brzycki: 1RM = weight × 36 ÷ (37 − reps)
The main result is the average of the two. The rep table runs the same formulas backward: it shows the weight you can expect to lift for each number of reps.
When not to trust it
- Above about 10 reps, the formulas give a less exact result. The calculator stops at 12 reps.
- The set must be hard: close to failure, with good form. An easy set gives a low estimate.
- The formulas come from barbell lifts in trained people. For machines, dumbbells and new lifters, treat the result as a rough guide.
The warm-up ladder is a common pattern of lighter sets before a heavy set: a few sets that get heavier with fewer reps. It is a guide, not a fixed rule.
How to use the result
Programs often give loads as a percent of 1RM. Many lifters work in sets of 6 to 12 reps, and the rep table shows a starting load for those sets. Retest every few weeks with a new hard set, because your 1RM goes up as you train.
Form guides for the lifts people test most:
Terms on this page: one-rep max, progressive overload.
Questions
How accurate is a one rep max calculator?
It is an estimate. The formulas work best for sets of up to about 10 reps taken close to failure. Above that, the error grows, and people with more fast or more slow muscle fibers can be off in either direction. Use the result to plan training loads, not as a record.
Which formula does this calculator use?
It shows two common formulas, Epley and Brzycki, and uses their average as the main result. For one rep, both give the weight you lifted. From 2 to 9 reps Epley gives the higher number, at 10 reps both are equal, and at 11 or 12 reps Brzycki is higher.
Do I need to test my real 1RM?
No. Most people do not need a true max test to train well. A hard set of 3 to 8 reps gives a useful estimate with less risk. If you do test a true max, use a spotter or safety bars, warm up well and stop when your form breaks down.
How do I use the percent chart?
Many programs give loads as a percent of your 1RM. Find the percent in the chart to get the weight for that set. Round to the plates you have; the chart rounds to 2.5 kg or 5 lb.
Can I use this for dumbbells or machines?
You can, but the formulas were built from barbell lifts. For dumbbells, machines and bodyweight exercises the estimate is rougher, so use it only as a guide.