Estimate from a set you already finished
One Rep Max Calculator
Enter the weight and reps from one clean set. Seven formulas estimate the single. The middle result becomes the training number, with weights you can actually load.
Enter a weight and at least one clean rep.
Back squat estimate
117.5 kg
Median of seven formulas: 116.6 kg, rounded to 2.5 kg.
The formulas run from 112.5 to 119 kg.
Above 10 reps, endurance starts to limit the set. A set of 3–8 reps tracks max strength more closely.
Seven formulas
| Formula | Estimate | Loadable |
|---|---|---|
| Epley | 116.7 kg | 117.5 kg |
| Brzycki | 112.5 kg | 112.5 kg |
| Lombardi | 117.5 kg | 117.5 kg |
| O'Conner | 112.5 kg | 112.5 kg |
| Wathan | 116.6 kg | 117.5 kg |
| Mayhew | 119 kg | 120 kg |
| Lander | 113.7 kg | 112.5 kg |
Training weights
Percentages of the loadable estimate. Strength work usually lives around 80–90%. Muscle-building sets often sit around 65–80%.
| Percent | Weight |
|---|---|
| 100% | 117.5 kg |
| 95% | 112.5 kg |
| 90% | 105 kg |
| 85% | 100 kg |
| 80% | 95 kg |
| 75% | 87.5 kg |
| 70% | 82.5 kg |
| 65% | 77.5 kg |
| 60% | 70 kg |
| 55% | 65 kg |
| 50% | 60 kg |
Warm-up to a top set
| Step | Load | Reps |
|---|---|---|
| Bar | 20 kg | 8 |
| 50% | 60 kg | 5 |
| 65% | 77.5 kg | 3 |
| 75% | 87.5 kg | 2 |
| 85% | 100 kg | 1 |
The seven formulas
A one-rep max is the heaviest weight you can lift for one complete rep on that exercise. These formulas work backwards from a lighter set. They are estimates, not a test.
If you enter 1 rep, every formula returns that weight. A finished single is already a max, so the math stays out of it.
| Formula | Equation |
|---|---|
| Epley | weight × (1 + reps / 30) |
| Brzycki | weight × 36 / (37 − reps) |
| Lombardi | weight × reps0.10 |
| O'Conner | weight × (1 + 0.025 × reps) |
| Wathan | 100 × weight / (48.8 + 53.8 × e−0.075 × reps) |
| Mayhew | 100 × weight / (52.2 + 41.9 × e−0.055 × reps) |
| Lander | 100 × weight / (101.3 − 2.67123 × reps) |
Brzycki sits below Epley on sets under 10 reps and matches it at 10. After 10 reps Brzycki runs higher. The gap between the lowest and highest formula is the uncertainty. Train from the median, the middle of the seven.
Example: 100 kg for 5 reps
A bar loaded to 100 kg for 5 clean reps produces this spread. Rounded to 2.5 kg, the training number is 117.5 kg.
| Formula | Estimate |
|---|---|
| Epley | 116.7 kg |
| Brzycki | 112.5 kg |
| Lombardi | 117.5 kg |
| O'Conner | 112.5 kg |
| Wathan | 116.6 kg |
| Mayhew | 119.0 kg |
| Lander | 113.7 kg |
| Median | 116.6 kg |
What to do with the estimate
Use the percentage table for the next session. If the formulas are far apart, keep the first heavy sets at or under the median until a cleaner set agrees with it.
- Count only reps that match the same depth, pause, and bar path.
- Bench, squat, and deadlift each need their own number. A squat estimate does not transfer to the bench.
- The exercise menu only names the lift. The formula stays the same. A note under the result means that lift sits outside the barbell compounds these equations were built on.
- Dumbbell entries are per hand. The calculator doubles them so the load is the pair.
- For pull-ups and dips, add bodyweight to the extra load. The estimate is for the total, not the belt alone.
- Update the estimate when you add reps at the same weight, or lift the same reps heavier. Every block is enough. Every session is not.
This is a planning estimate. It is not a medical clearance and it is not a dare to max out. Use a spotter and a rack for heavy singles.
Questions
How many reps should I enter?
Use a hard set of 3 to 8 clean reps. Above 10 reps, fatigue plays a bigger part and the estimate is less stable.
Why do the seven formulas disagree?
Each formula fits a different curve from reps to a single. They sit closer together around 5 reps and spread out as the rep count climbs. The median is the training number.
Can I use this for dumbbells or pull-ups?
Yes. Choose Dumbbell and enter the weight in one hand. Choose Body + load for dips or pull-ups and enter bodyweight plus whatever you added.
Is this my real one-rep max?
No. It is an estimate from a submax set. A true max is a single you actually lift. Use a spotter if you test a heavy single.
More calculators
- Bench press, squat, and deadlift each keep their own estimate.
- Percentages turn a known max into bar weight.
- Training max takes 90% or 95% of that max for day-to-day loads.
- Plates splits a target across the two sides of the bar.
- RPE estimates a max when the set stopped with reps still in reserve.
- Total adds squat, bench, and deadlift.
- Score turns that total into DOTS, Wilks, and IPF GL points.