1RM calculator
Enter the weight you lifted and how many reps you got, and this estimates your one-rep max: the most you could lift for a single rep. It runs three standard formulas (Epley, Brzycki and Lombardi), averages them, and gives you a table of training weights from 50% to 100% of that max.
Input Data
How is a one-rep max calculated from reps?
Each formula scales the weight you lifted by how many reps you got with it:
- Epley: weight × (1 + reps ÷ 30)
- Brzycki: weight × 36 ÷ (37 − reps)
- Lombardi: weight × reps0.10
For example, 225 lb for 5 reps gives about 263 lb by Epley, 253 lb by Brzycki and 264 lb by Lombardi, so the average estimate is about 260 lb. The full walk-through is in how to calculate your one-rep max.
What percentage of my max is a set of 5?
A set of 5 taken to failure is roughly 86% to 89% of your one-rep max. This table shows what each rep count works out to under the two most common formulas, so you can read it in either direction.
| Reps to failure | % of 1RM (Epley) | % of 1RM (Brzycki) |
|---|---|---|
| 1 | 100.0% | 100.0% |
| 2 | 93.8% | 97.2% |
| 3 | 90.9% | 94.4% |
| 4 | 88.2% | 91.7% |
| 5 | 85.7% | 88.9% |
| 6 | 83.3% | 86.1% |
| 7 | 81.1% | 83.3% |
| 8 | 78.9% | 80.6% |
| 9 | 76.9% | 77.8% |
| 10 | 75.0% | 75.0% |
| 12 | 71.4% | 69.4% |
How programs use those percentages is covered in one-rep max percentages explained, and if you need to load the bar for one of them, the plate calculator does the arithmetic. Once you have a max, the strength standards calculator shows how it compares for your age and bodyweight.
Questions
How accurate is an estimated one-rep max?
It is an estimate, and it is closest when the set was 10 reps or fewer and taken close to failure. Past about 10 reps the formulas drift apart, so use a heavier set of 3 to 6 reps if you want a number to program from.
Which formula is best: Epley, Brzycki or Lombardi?
None is best for everyone. Epley and Brzycki agree almost exactly at 10 reps and stay close below that; Lombardi reads a little higher at low reps and lower at high reps. The calculator averages all three so no single formula's bias decides your number.
Does the calculator work in kilograms?
Yes. The formulas only use ratios, so enter the weight in kilograms and the estimate and the percentage table come out in kilograms.
Should I test a true one-rep max instead?
Most lifters do not need to. An estimate from a hard set of 3 to 5 reps is enough to set training weights, and it carries less risk and fatigue than a true max attempt.