RPE and RIR Explained
RPE (rate of perceived exertion) is a 1 to 10 score for how hard a set felt. RIR (reps in reserve) is how many more good reps you could have done. In lifting they’re two sides of one scale: RPE 10 = 0 RIR, RPE 9 = 1 RIR, RPE 8 = 2 RIR.
Key takeaways
- RPE rates how hard a set felt, from 1 to 10. RIR is how many good reps you had left.
- RPE 10 means no reps left, RPE 8 means about 2 left.
- Add your reps in reserve to the reps you did to estimate your max from a set you didn’t take to failure.
The RPE scale for lifting
| RPE | Reps in reserve | What it feels like |
|---|---|---|
| 10 | 0 | Could not do another rep. |
| 9.5 | 0 to 1 | Maybe one more, maybe not. |
| 9 | 1 | One more rep, definitely. |
| 8.5 | 1 to 2 | One for sure, maybe two. |
| 8 | 2 | Two more reps. |
| 7 | 3 | Three more reps. Heavy but comfortable. |
| 6 and below | 4+ | Warm-up or speed work. |
This version of RPE was described by Zourdos and colleagues in 2016, and Helms and colleagues explained how to use it in training the same year. Older RPE scales measured general effort. This one ties the score to reps left, which makes it more useful for lifting.
Why use RPE and RIR?
- It adjusts to your day. If you slept badly, the same weight feels heavier, and RPE lets you lighten it.
- It works without a known max. “3 sets of 5 at RPE 8” works whether you know your 1RM or not.
- It helps estimate your max from sets that were not all-out. Add the reps in reserve to the reps you did, then use a 1RM formula.
An example
You squat 120 kg for 4 reps and feel you had 2 left. That’s RPE 8. Treat it as 6 reps to failure: 120 × 6 gives an estimated max of about 142.3 kg. Now your program says “3 reps at RPE 8” next week. That’s like a 5-rep effort (3 reps plus 2 in reserve), so you would load about 122.5 kg. The RPE calculator does all of this for you.
How to rate RPE well
- Rate right after the set.
- Watch bar speed. When the last rep slows a lot, you’re near RPE 9 to 10.
- Check yourself sometimes. On a safe exercise, do one more rep than you planned and see if your guess was right.
- Expect to improve. In the Zourdos study, experienced lifters rated their sets more accurately than novices.
How to use RPE in a program
Programs that use RPE usually give a target, such as “3 × 5 @ RPE 8”. You pick a weight you think will be RPE 8 for 5 reps. After the first set, rate it. If it was RPE 9, drop the weight a little for the next sets. If it was RPE 7, add a little. Over a few weeks you learn which weights match which RPE for you.
Some programs also use RPE to stop sets, for example “work up to a single at RPE 8, then do back-off sets at 85% of that weight”. This lets your training follow your strength on the day.
Common RPE mistakes
- Rating too low. Many people think they had more reps left than they did, especially early on.
- Rating on effort, not reps. A set can feel tiring and still have 3 reps left. Ask “how many more could I do?”
- Using RPE for very high reps. Above about 12 reps, fatigue and breathing make it hard to judge reps left.
RPE or percentages?
You don’t have to choose. Many lifters plan with percentages from the one rep max chart, then use RPE to adjust on the day. If the planned weight feels harder than the target RPE, drop a little. If it feels easier, add a little.
Safety first: this guide is general information, not medical advice. Use safety pins or a spotter for heavy sets, and stop if you feel pain.
Frequently asked questions
What is the difference between RPE and RIR?
They describe the same thing from two directions. RIR is the number of reps you had left. RPE is a 1 to 10 score where 10 means no reps left. RPE = 10 − RIR.
What RPE should most sets be?
Many programs put most working sets at RPE 6 to 8, leaving 2 to 4 reps in reserve, with occasional heavier sets at RPE 9 or above. Follow what your program or coach sets.
Is RPE accurate?
It gets more accurate with practice. Research found experienced lifters rated their sets more accurately than novices, especially with heavier loads.
Can I use RPE to find my 1RM?
Yes. Add your reps in reserve to the reps you did and use a 1RM formula, or enter the set and RPE in our RPE calculator.
Sources
- Zourdos MC, Klemp A, Dolan C, et al. Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. Journal of Strength and Conditioning Research. 2016;30(1):267-275. PubMed 26049792
- Helms ER, Cronin J, Storey A, Zourdos MC. Application of the repetitions in reserve-based rating of perceived exertion scale for resistance training. Strength and Conditioning Journal. 2016;38(4):42-49. PubMed 27531969