Strength
RPE vs RIR: how to use the RPE scale in strength training
Percentages of your one-rep max work well on paper, but you are not equally strong every day. Sleep, stress, diet and fatigue all change what a “75%” set feels like. RPE — rating of perceived exertion — lets you adjust the weight to how you actually perform on the day, and it has become standard in modern strength programs. This guide explains the scale, how to rate sets honestly, and how to turn RPE into working weights.
Why lifters use RPE
Percentage-based programs assume your max is fixed. In reality it moves: you might be 5% stronger on a great day and 5% weaker after a bad night’s sleep. A fixed 85% can be easy on Monday and a grind on Friday.
RPE flips the approach. Instead of “5 reps at 85%”, the program says “5 reps at RPE 8”, and you choose the weight that makes that true today. This is often called autoregulation: the training adjusts to you, rather than the other way round.
The RPE and RIR scale
The original RPE scale, created by Gunnar Borg, runs from 6 to 20 and was designed for endurance exercise. Strength coaches adapted it into a 1–10 scale based on reps in reserve (RIR): how many more good reps you could have done before failure. Powerlifting coach Mike Tuchscherer popularised it, and Zourdos and colleagues described and tested a formal version in 2016.
| RPE | Reps in reserve | What it feels like |
|---|---|---|
| 10 | 0 | Maximal — no more reps, no more weight |
| 9.5 | 0 | No more reps, but maybe slightly more weight |
| 9 | 1 | One more rep was possible |
| 8.5 | 1–2 | Definitely one more, maybe two |
| 8 | 2 | Two more reps were possible |
| 7.5 | 2–3 | Two more for sure, maybe three |
| 7 | 3 | Three more reps; bar speed still quick |
| 6 and below | 4+ | Warm-up or technique work |
So RPE 8 and “2 RIR” describe the same set. Use whichever wording your program uses.
How to rate a set honestly
- Rate it straight after the last rep, before you rack the bar and walk away.
- Ask “how many more clean reps could I have done?”, not “how hard did it feel?”.
- Count only reps with good technique. A rep you would grind out with a broken position doesn’t count as “in reserve”.
- Watch bar speed: a sharp slowdown on the last rep usually means RPE 9 or higher.
- Film occasional sets. Watching the video helps you calibrate what RPE 8 really looks like.
Expect to be off at first. Research by Zourdos and colleagues found that ratings tend to be more accurate close to failure and that experienced lifters rate more accurately, so newer lifters often underestimate how many reps they have left — calling something an 8 when they actually had four or five in the tank.
Reading an RPE chart
An RPE chart links reps and RPE to a percentage of your one-rep max. Each row is a number of reps; each column is an RPE. A few rows from the Reactive Training Systems chart used by our calculator:
| Reps | RPE 10 | RPE 9 | RPE 8 | RPE 7 |
|---|---|---|---|---|
| 1 | 100% | 95.5% | 92.2% | 89.2% |
| 3 | 92.2% | 89.2% | 86.3% | 83.7% |
| 5 | 86.3% | 83.7% | 81.1% | 78.6% |
| 8 | 78.6% | 76.2% | 73.9% | 70.7% |
Moving right (lower RPE) or down (more reps) both mean a lighter weight. The RPE calculator shows the full 10 × 8 chart with your own weights filled in.
Estimating your 1RM from RPE
Because each cell is a percentage of your max, one honest set gives you an estimate:
Estimated 1RM = weight lifted ÷ chart percentage
Say you squat 140 kg for 3 reps at RPE 8. The chart puts 3 reps at RPE 8 at 86.3% of your max, so your estimated 1RM is 140 ÷ 0.863 ≈ 162.2 kg — no max-out required.
Estimates are most reliable from low-rep sets at RPE 8 or above. A set of 10 at RPE 6 involves a lot more guesswork, both in the rating and in the chart.
Programming with RPE
Once you have an estimated max, the chart works in reverse to pick the weight for any set. If the program says 5 reps at RPE 8, that’s 81.1% of 162.2 kg ≈ 131.5 kg. Common ways to structure a session:
- Top set and back-offs. Work up to one set at the target RPE (for example 3 reps at RPE 8), then drop the weight by 5–10% for several back-off sets.
- Fixed sets at a target RPE. Do 4 × 5 at RPE 7–8, adjusting the weight if a set comes in too easy or too hard.
- RPE stops. Repeat sets at the same weight until one reaches the target RPE — useful for managing fatigue.
Common mistakes
- Rating the effort, not the reps left. A set can feel brutal and still be RPE 7 if the bar was moving fast.
- Ego rating. Calling a grinder an RPE 8 so you can add weight next time only leads to missed lifts.
- Trusting the chart over your history. Some people can do more reps at a given percentage than the chart predicts, others fewer. If your estimates are consistently off, adjust your targets.
- Using RPE for everything. Isolation exercises with high reps are hard to rate accurately; simple rep targets often work better there.
Who should use RPE?
RPE works best for intermediate and advanced lifters who can judge their sets and whose progress no longer comes session to session. Beginners usually do better with simple linear progression — add a little weight each time — while they learn what a hard set feels like. A good way to start is to rate every set on the side for a month, without changing the program, and compare your ratings with how many reps you actually get when you test a set to near failure.
Try the RPE Calculator & ChartEstimate your 1RM from any hard set, then pick weights by reps and RPE.Frequently asked questions
Is RPE the same as RIR?
For lifting, yes in practice. The resistance-training RPE scale is defined by reps in reserve: RPE 10 is 0 reps left, RPE 9 is 1, RPE 8 is 2, and so on. RPE 9.5 means no more reps but maybe a little more weight.
What RPE should I train at?
Most working sets for strength and muscle land between RPE 7 and 9 — one to three reps short of failure. Heavy singles and top sets often go to RPE 8–9, while technique and volume work sits around RPE 6–8.
How accurate is an RPE-based 1RM estimate?
Good enough to guide training, especially from sets of 1–5 reps at RPE 8 or higher. Estimates from high-rep or low-RPE sets are less reliable, and individuals differ in how many reps they can do at a given percentage.
What is the difference between RPE 9 and 9.5?
At RPE 9 you could have done one more rep. At 9.5 you couldn’t have done another rep, but you could have handled slightly more weight for the same reps.
Should beginners use RPE?
Beginners can learn it, but they usually progress fastest by adding a little weight every session. Rating sets on the side, without relying on the numbers, is a good way to practise.
References
- Zourdos MC, Klemp A, Dolan C, et al. Novel resistance training-specific rating of perceived exertion scale measuring repetitions in reserve. J Strength Cond Res. 2016;30(1):267–275. pubmed.ncbi.nlm.nih.gov/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 Cond J. 2016;38(4):42–49. pubmed.ncbi.nlm.nih.gov/27531969/
General fitness information, not medical advice. Figures are estimates calculated with the formulas cited above. Check with a doctor or qualified coach before major changes to diet, supplements or training. Read the full medical disclaimer and how we write and check these pages in our editorial policy.
