Calculating your estimated 1-rep max (epley) is straightforward once you know the One Rep Max formula and what each input means. This guide explains the method in plain language, walks through a manual calculation, and gives worked examples you can follow — then you can do it instantly with the One Rep Max Calculator.
What is One Rep Max?
The One Rep Max calculation tells you your estimated 1-rep max (epley) from a few simple inputs. The figure you are solving for here is the estimated 1-rep max (epley).
The One Rep Max formula
The core formula is:
Estimated 1-rep max (Epley) = Weight lifted × (1 + Repetitions completed ÷ 30)Here is what each input means:
- Weight lifted — a value measured in kg. Example: 80 kg.
- Repetitions completed — a number. Example: 5.
How to calculate it step by step
- Write down the weight lifted (for example, 80 kg).
- Write down the repetitions completed (for example, 5).
- Apply the formula above to get your estimated 1-rep max (epley).
- Double-check the result with the One Rep Max Calculator.
Worked examples
Example 1
| Input / Output | Value |
|---|---|
| Weight lifted | 80 kg |
| Repetitions completed | 5 |
| Estimated 1-rep max (Epley) | 93.3 |
| 1RM (Brzycki) | 90.0 |
| 90% of 1RM | 84.0 |
With weight lifted of 80 kg and repetitions completed of 5, the estimated 1-rep max (epley) works out to 93.3.
Example 2
With weight lifted of 160 kg and repetitions completed of 5, the estimated 1-rep max (epley) works out to 186.7.
| Result | Value |
|---|---|
| Estimated 1-rep max (Epley) | 186.7 |
| 1RM (Brzycki) | 180.0 |
| 90% of 1RM | 168.0 |
Example 3
With weight lifted of 40 kg and repetitions completed of 5, the estimated 1-rep max (epley) works out to 46.7.
| Result | Value |
|---|---|
| Estimated 1-rep max (Epley) | 46.7 |
| 1RM (Brzycki) | 45.0 |
| 90% of 1RM | 42.0 |
Tips for an accurate result
- Keep your units consistent — mixing, say, months with years or grams with kilograms is the most common source of error.
- Round only at the very end. Rounding inputs early can shift the final answer noticeably.
- Re-run the numbers whenever an input changes, rather than estimating from an old result.
- These figures are general estimates, not medical advice — check with a qualified professional before acting on them.
Prefer not to do the maths by hand? — the One Rep Max Calculator does it instantly, for free, with the formula and a worked example built in.
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