What RPE means on the gym floor
RPE stands for rating of perceived exertion. On the scale lifters use, the rating answers one question: how many good reps were left when you racked the bar? A 10 means none. An 8 means two. Rating a set this way lets a program ask for an effort instead of a fixed number, so the weight moves with you on the days you are fresh and on the days you are not.
RPE and RIR are the same number, counted from opposite ends
RIR stands for reps in reserve. Subtract the RPE from 10 and you have it: RPE 8 is 2 RIR, RPE 9.5 is half a rep in reserve. Some coaches write programs one way and some the other. The toggle above switches the labels without changing a thing about the result, so you can work in whichever your program uses.
Rate the last rep, not the whole session
The rating describes bar speed and how close the set came to failing, not how tired you feel or how much you dreaded the lift. Judge it from the final rep: did it slow down, did the bar stall, could you have finished another one to the same standard? If you are not sure whether it was an 8 or a 9, rate it the lower of the two and keep the weight honest.
The effort scale, rating by rating
What each rating on the scale is describing.
| RPE | RIR | Feel | What it means |
|---|---|---|---|
| 10 | 0 | Maximal | Nothing left. The last rep was the last rep. |
| 9.5 | 0.5 | Near maximal | Maybe a little more weight, but no more reps. |
| 9 | 1 | Very hard | One more rep was there. |
| 8.5 | 1.5 | Hard | One more rep for sure, possibly two. |
| 8 | 2 | Hard | Two more reps were there. |
| 7.5 | 2.5 | Challenging | Two more reps for sure, possibly three. |
| 7 | 3 | Challenging | Three more reps were there. |
| 6.5 | 3.5 | Moderate | Three more reps for sure, possibly four. |
| 6 | 4 | Moderate | Four more reps were there. |
Where these weights come from
Reps in reserve are added to the reps you finished, which gives the set an estimated length at failure. That number goes through the same equations as our one rep max calculator: Epley by default, with Brzycki and Lombardi for comparison. A set of 5 at RPE 8 is treated as a set of 7 to failure, so the two tools always agree about the same set.
This is a practical approximation. The percentages here are calculated, not taken from a published lookup table, and no equation accounts for the differences between exercises.
Where each rating tends to belong
Most working sets in a strength or hypertrophy block land somewhere between RPE 7 and RPE 9: hard enough to drive an adaptation, far enough from failure that technique holds and the next session is not compromised. Ratings of 9.5 and 10 cost more to recover from, which is why they usually appear sparingly. Lighter ratings have their place in warm ups, technique work, and the first sessions after a break. Your program decides the number. This calculator only tells you what weight it corresponds to.
How accurate is an RPE rating?
The RIR-based scale was tested against bar speed in squatters, and the ratings tracked velocity closely enough to support using them, more so in experienced lifters than in novices. A separate study of 81 adults found estimates of reps remaining were more accurate closer to failure, so an 8 or a 9 is a better input here than a 6.
There is a second source of error on top of the rating. The reps possible at a given percentage of 1RM vary between people and between exercises, which a general equation cannot know about. Treat the output as a starting weight you adjust from, and let the effort rating on the day overrule the number on the screen.
Already know your max?
If you would rather start from a max you have tested or estimated, the one rep max calculator takes a set and gives you a percentage table to work from.
Frequently asked questions
What does RPE 8 mean?
RPE 8 means you finished the set with two good reps left in the tank. On the reps in reserve scale that is 2 RIR. It is a hard working set, close enough to failure to be productive, far enough from it that the last rep still looked like the first.
How do I convert RPE to reps in reserve?
Subtract the rating from 10. RPE 10 is 0 reps in reserve, RPE 9 is 1, RPE 8 is 2, and so on. Half ratings work the same way: RPE 8.5 is one and a half reps in reserve, which in practice means one for certain and possibly two.
How do I turn RPE into a percentage of my 1RM?
Add your reps in reserve to the reps you completed, then read that total as a set taken to failure. The chart above does this for you: find your rep count, read across to your rating, and you have the weight. Switch the formula to see how much the estimate moves.
Should I train to RPE 10?
Sets at RPE 10 end at failure and cost more to recover from, so most programs use them sparingly or not at all. Training between RPE 7 and 9 keeps the effort high while leaving something in reserve for technique and for the rest of the week. Follow the ratings your program prescribes.
Is RPE better than training with percentages?
They answer different questions. A percentage fixes the weight in advance; a rating lets the weight respond to how the day is going. Many programs use both, setting a percentage as the starting point and a rating as the limit. This calculator connects the two so you can move between them.
Can beginners use RPE?
Yes, though the ratings get more accurate with experience. Estimates of reps remaining are most reliable near failure, so if you are new to rating sets, start by asking the question only on your heavier work and take a few sets close to failure to calibrate what the top of the scale actually feels like.
Sources
Peer-reviewed research on the RIR-based scale and on how accurately lifters judge the reps they have left. These studies inform the guidance above. They do not validate this calculator or the percentages it derives.
- Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve
Zourdos MC, Klemp A, Dolan C, Quiles JM, Schau KA, Jo E, et al. Journal of Strength and Conditioning Research. 2016;30(1):267–275.
Introduces the reps-in-reserve scale and compares ratings with bar velocity in experienced and novice squatters.
- Application of the Repetitions in Reserve-Based Rating of Perceived Exertion Scale for Resistance Training
Helms ER, Cronin J, Storey A, Zourdos MC. Strength and Conditioning Journal. 2016;38(4):42–49.
Describes how the scale is applied in practice and where it sits alongside percentage-based loading.
- Accuracy in Estimating Repetitions to Failure During Resistance Exercise
Hackett DA, Cobley SP, Davies TB, Michael SW, Halaki M. Journal of Strength and Conditioning Research. 2017;31(8):2162–2168.
Examines how accurately lifters judge reps remaining, and how training status and exercise affect it.
- Maximal Number of Repetitions at Percentages of the One Repetition Maximum: A Meta-Regression and Moderator Analysis of Sex, Age, Training Status, and Exercise
Nuzzo JL, Pinto MD, Nosaka K, Steele J. Sports Medicine. 2024;54:303–321.
Examines variation in the relationship between reps and percentage of 1RM.