Calculator
What the One Rep Max Calculator does
One Rep Max Calculator: calculates Estimated 1RM and Epley Estimate from Weight Lifted and Reps Completed. Example: weight lifted 60 kg and reps completed 5 gives estimated 1RM 68.8.
From Weight Lifted and Reps Completed, this tool derives Estimated 1RM and Epley Estimate. You can nudge a single number and watch the effect straight away.
Most people who open the One Rep Max Calculator are someone starting a new plan. A single number is most useful as a trend over time rather than a one-off judgement.
There is no account, no upload and no server round trip, because the page does the work itself.
The method, a field-by-field reference and a worked example built from the defaults are all on this page.
What do the One Rep Max Calculator fields mean?
The One Rep Max Calculator uses 2 inputs. Pre-filled inputs double as documentation: each one shows what a reasonable value looks like.
| Field | What to enter | Default |
|---|---|---|
| Weight Lifted | measured in kg; accepts 1 to 500 | 60 |
| Reps Completed | accepts 1 to 20 | 5 |
How does the One Rep Max Calculator work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same calculation.
Values are checked first: an out-of-range or non-numeric entry names the offending field instead of returning nonsense.
Worked example
These are the values the One Rep Max Calculator loads by default, and the result it produces from them. This is the worked example the page starts from, reproduced here so you can check the arithmetic.
| Weight Lifted | 60 kg |
|---|---|
| Reps Completed | 5 |
| Estimated 1RM | 68.8 |
|---|---|
| Epley Estimate | 70.0 |
| What this means | Estimated 1-rep max ≈ 68.8 kg. Use for programming: warm up carefully. |
How to use it
- Fill in Weight Lifted in kg (1 to 500).
- Type Reps Completed (1 to 20).
- Live output means you can search for a target value by nudging an input up and down.
- The panel reports Estimated 1RM, Epley Estimate and What this means.
- Copy Link puts the current inputs in the URL, so bookmarking it brings the same numbers back.
What this tool does not do
- Population-level formulas cannot account for medical conditions, medication or pregnancy.
- This is a screening estimate, not a diagnosis.
- There is no audit trail: if you need one, record the inputs alongside the output.
- Confirm the units before you act on the output. The arithmetic is only as sound as what went in.
Frequently asked questions
Enter Weight Lifted in kg. The unit is shown beside each box, and the result carries its own label, so there is nothing to convert by hand.
Weight Lifted accepts 1 to 500 kg. If a value falls outside, the tool says which field is at fault instead of guessing.
With the values loaded when the page opens, estimated 1RM comes out as 68.8. The figure is derived from the inputs above, so it updates whenever they do.
No. The calculation is local, so no health information ever reaches a server.
No. There is no account, no usage cap and no trial period. The site is funded by advertising rather than by charging for the tools.
The number is exact; its meaning is approximate. Two people with identical results can be in genuinely different situations, which is why this is a screening tool rather than a diagnostic one.