RPE & e1RM Calculator
Enter a set you've done (weight, reps and how hard it felt) and get an estimated one-rep max (e1RM). Or start from your e1RM and get a weight for a target like "5 reps at RPE 8". It's free and needs no account.
How the calculator handles your input:
- RPE is accepted from 6 to 10 in half steps. Anything else is snapped to the nearest 0.5, with a note such as "RPE 8.7 rounded to 8.5". If it's still outside 6–10 after snapping, you'll see "RPE must be between 6 and 10".
- The RPE chart covers 1 to 12 reps.
- e1RM at 1 rep is the weight you lifted.
- From 2 to 10 reps you get an e1RM. At 11–12 reps, Epley and Brzycki results come with a "less reliable" note. Above 12 reps no e1RM is shown.
- Method: Epley is the default, and you can switch to Brzycki in settings. If you enter an RPE, the calculator uses the RPE chart instead.
RPE and RIR in one minute
RPE (rating of perceived exertion) is a 1–10 score for how hard a set was. In lifting it's usually tied to RIR, the reps you had left in reserve when you racked the bar:
| RPE | Meaning | RIR |
|---|---|---|
| 10 | Max effort, nothing left | 0 |
| 9 | One more rep was there | 1 |
| 8 | Two more reps | 2 |
| 7 | Three more reps | 3 |
| 5–6 | Four to six more | 4–6 |
That's the scale Zourdos and colleagues tested in 2016. They reported that it was a practical way to regulate daily training load. Half-points such as 8.5 mean "maybe one more rep, definitely not two". In RTS-style training, RPEs below 7 are usually for warm-ups and lighter work.
e1RM formulas
These formulas assume the set was taken to failure, or very close to it.
Epley: e1RM = weight × (1 + reps ÷ 30)
Brzycki: e1RM = weight × 36 ÷ (37 − reps)
Both are rough guides. Brzycki wrote that his equation is valid when the reps are under 10 and gets less accurate above that, and the same caution is sensible for Epley. Epley also gives slightly more than the bar weight for a single (100 kg × 1 → 103.3 kg), so treat a true single as the weight itself.
Worked examples
| Set (to failure) | Epley | Brzycki |
|---|---|---|
| 100 kg × 5 | 100 × (1 + 5/30) = 116.7 kg | 100 × 36/32 = 112.5 kg |
| 120 kg × 8 | 120 × (1 + 8/30) = 152.0 kg | 120 × 36/29 = 149.0 kg |
The two formulas drift further apart as reps go up. That's one more reason to estimate from lower-rep sets.
The RPE chart method
An RPE chart, popularised by Mike Tuchscherer of Reactive Training Systems (RTS), lists the percentage of 1RM that a given reps-and-RPE pairing usually corresponds to. Here's part of the commonly published version. Charts vary, so check it against what your coach or federation uses:
| Reps | RPE 10 | RPE 9.5 | RPE 9 | RPE 8.5 | RPE 8 | RPE 7.5 | RPE 7 |
|---|---|---|---|---|---|---|---|
| 1 | 100% | 97.8% | 95.5% | 93.9% | 92.2% | 90.7% | 89.2% |
| 2 | 95.5% | 93.9% | 92.2% | 90.7% | 89.2% | 87.8% | 86.3% |
| 3 | 92.2% | 90.7% | 89.2% | 87.8% | 86.3% | 85.0% | 83.7% |
| 4 | 89.2% | 87.8% | 86.3% | 85.0% | 83.7% | 82.4% | 81.1% |
| 5 | 86.3% | 85.0% | 83.7% | 82.4% | 81.1% | 79.9% | 78.6% |
| 6 | 83.7% | 82.4% | 81.1% | 79.9% | 78.6% | 77.4% | 76.2% |
Notice the diagonal: 3 reps at RPE 10 and 1 rep at RPE 8 are both 92.2%. Either way, you'd have stopped two reps short of a triple.
Set to e1RM: 140 kg × 3 @ RPE 8 → 86.3% → 140 ÷ 0.863 = 162.2 kg e1RM.
e1RM to set: e1RM 180 kg, target 5 @ RPE 8 → 81.1% → 180 × 0.811 = 146.0 kg. Load 145 kg (20 kg bar, 62.5 kg a side: 25 + 25 + 10 + 2.5). The calculator rounds the target to the nearest 2.5 kg, and 146.0 kg rounds to 145. Let the RPE of your first set tell you whether to adjust.
A rougher shortcut is to add RIR to the reps and use a formula. For example, 100 kg × 5 @ RPE 8 counts as 7 reps: Epley gives 123.3 kg and Brzycki gives 120.0 kg.
Tuchscherer himself cautions against using his chart to estimate a 1RM; he meant it for choosing training loads. Charts are averages, so yours may differ by lift and by person. Treat any e1RM as a planning number, not a max to test.
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Check your numbers and train safely
An e1RM is an estimate. Don't attempt a new max because a formula says you can. Start conservatively, use safeties or a spotter, and stop if something feels wrong.
Sources (checked 19 October 2026):
- Zourdos MC et al. "Novel resistance training–specific rating of perceived exertion scale measuring repetitions in reserve." J Strength Cond Res 30(1): 267–275, 2016. https://pubmed.ncbi.nlm.nih.gov/26049792/
- Helms ER et al. "Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training." Strength Cond J 38(4): 42–49, 2016. https://pmc.ncbi.nlm.nih.gov/articles/PMC4961270/
- Brzycki M. "Strength testing: predicting a one-rep max from reps-to-fatigue." JOPERD 64(1): 88–90, 1993. https://doi.org/10.1080/07303084.1993.10606684
- Epley B. Poundage Chart. Boyd Epley Workout. Lincoln, NE: Body Enterprises, 1985 (not online; formula as cited in the strength-research literature, e.g. https://opensiuc.lib.siu.edu/cgi/viewcontent.cgi?article=1744&context=gs_rp).
- Tuchscherer M. "Beginning RTS." Reactive Training Systems. https://store.reactivetrainingsystems.com/blogs/rts-basics/beginning-rts