RPE Calculator
Enter a recent set with your RPE rating to estimate your one rep max and see what weight to use for any rep and RPE combination.
What is RPE in strength training?
RPE stands for Rate of Perceived Exertion. In strength training, it’s a scale from 1 to 10 that measures how hard a set felt, based on how many reps you had left in the tank. The system was adapted for powerlifting by Mike Tuchscherer of Reactive Training Systems and has become the standard for autoregulated training.
An RPE of 10 means you couldn’t have done another rep — it was a true max effort. An RPE of 9 means you had one more rep left. RPE 8 means two reps left, and so on. Half values (like 8.5) mean you might have had another rep — you’re not quite sure.
RPE vs RIR — what’s the difference?
RPE and RIR (Reps in Reserve) describe the same thing from opposite directions. RPE 8 is the same as 2 RIR — both mean you had two reps left. Some lifters prefer one scale over the other, but they’re interchangeable:
| RPE | RIR | Meaning |
|---|---|---|
| 10 | 0 | Maximum effort, no reps left |
| 9.5 | 0.5 | Could maybe do one more |
| 9 | 1 | One rep left in the tank |
| 8.5 | 1.5 | Could maybe do two more |
| 8 | 2 | Two reps left |
| 7.5 | 2.5 | Could maybe do three more |
| 7 | 3 | Three reps left |
| 6.5 | 3.5 | Could maybe do four more |
| 6 | 4 | Four reps left |
How to use the RPE calculator
This calculator helps you figure out what weight to use for your next set or session. Here’s the typical workflow:
You complete a set — say, 100 kg for 5 reps, and it felt like RPE 8 (you could have done 2 more reps). Enter those numbers into the calculator. It estimates your 1RM based on where that set falls on the RPE chart, then fills in the entire table with real weights.
Now you can look up any combination. If your program says to do 3 reps at RPE 9, find that cell in the chart and you’ll see exactly what weight to load. No mental math, no guessing.
The chart is also useful for planning backoff sets. After a heavy top set, you might want to do volume work at a lower RPE. The chart shows you exactly how much to drop.
Tips for accurate RPE ratings
RPE is a skill that improves with practice. New lifters often underestimate or overestimate their RPE, which makes the calculator less reliable. A few things to keep in mind:
RPE works best in the 6–9.5 range. Below RPE 6, the estimates become unreliable because you’re too far from failure to judge accurately. At RPE 10, you need to genuinely hit failure — not just feel tired.
The calculator is most accurate for compound barbell lifts like squat, bench press, and deadlift. Isolation exercises and machine work have more variability in the RPE-to-percentage relationship.
Fatigue matters. Your RPE 8 on a fresh first set is different from RPE 8 on your fifth set. The calculator gives you a snapshot based on one set, so use it as a guide rather than gospel.
If you’re new to RPE, start by rating every set for a few weeks without changing your programming. You’ll calibrate your internal sense of effort, and the ratings will get more accurate over time.