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RIR in lifting: meaning, RPE chart, and how to use it.
Repetitions in reserve gives lifters a simple language for how close a set came to failure. It is useful for programming effort, but it remains a subjective estimate.
Published and last reviewed September 14, 2026 · 8-minute read
RIR to RPE chart
RIR describes repetitions remaining. Resistance-training RPE expresses the same idea on a 1 to 10 effort scale. The simple conversion below is intended for the scale’s commonly used whole-number range near failure.
| RIR | RPE | Plain-language meaning |
|---|---|---|
| 0 RIR | RPE 10 | No additional complete repetition was available. |
| 1 RIR | RPE 9 | You estimate that one complete repetition remained. |
| 2 RIR | RPE 8 | You estimate that two complete repetitions remained. |
| 3 RIR | RPE 7 | You estimate that three complete repetitions remained. |
| 4 RIR | RPE 6 | You estimate that four complete repetitions remained. |
The original resistance-training-specific scale uses more nuance than this whole-number chart, including half steps and descriptive ranges farther from failure. Do not treat the conversion as a physiological measurement.
A practical example
What happened
You complete 8 repetitions of a squat and believe you could have completed 2 more with the same technique. You record 2 RIR, which corresponds to RPE 8 on the scale.
What it means
The entry communicates your perceived proximity to failure for that set. It does not prove that exactly 10 repetitions were possible, and it does not prescribe the next load by itself.
How to use RIR
Set a target
Choose the intended effort before the set according to the program, exercise, and goal.
Complete the set
Keep technique and range of motion consistent enough for the estimate to mean something.
Rate it immediately
Record how many additional complete repetitions you believe were available.
Review the pattern
Compare several similar sets and sessions instead of overreacting to one rating.
When the same planned load suddenly feels much harder or easier, RIR can add context that load and repetitions alone miss. It is most useful when logged consistently beside the actual exercise performance.
How accurate is RIR?
RIR is not perfectly accurate. A scoping review and exploratory meta-analysis covering 12 studies found that participants underpredicted repetitions to task failure by 0.95 repetitions on average, with considerable variation. Estimates tended to improve closer to failure, with heavier loads, and in lower-repetition sets. Training background did not clearly explain accuracy.
Use calibration, not false precision
Occasionally comparing an honest prediction with the repetitions actually available can help a healthy, experienced lifter understand personal error. Do this only where training to failure is appropriate and safe. Technique breakdown, pain, or unsafe exercise setup should end a set regardless of a planned RIR target.
Does hypertrophy require 0 RIR?
No study establishes that every working set must reach momentary muscular failure. A 2023 systematic review found no clear hypertrophy advantage for momentary failure over non-failure training. A 2024 exploratory meta-regression found that hypertrophy tended to improve as sets ended closer to failure, while also stating that the exact relationship remains unclear.
The responsible conclusion is narrower than either extreme: proximity to failure matters, but 0 RIR is not a universal requirement. Exercise type, volume, fatigue, discomfort, technique, safety, and the rest of the program all affect the decision.
Frequently asked questions
What does RIR mean in lifting?
RIR means repetitions in reserve. It is the number of additional repetitions you believe you could complete before reaching task failure at the end of a set.
Is 2 RIR the same as RPE 8?
Yes, on the commonly used resistance-training RIR-based RPE scale. RPE 10 corresponds to 0 RIR, RPE 9 to 1 RIR, and RPE 8 to 2 RIR.
Is RIR accurate?
RIR is a subjective estimate, not a measured count. A research review found imperfect predictions overall, with estimates tending to improve closer to failure, with heavier loads, and in lower-repetition sets.
Should every set reach 0 RIR?
No. Current evidence does not establish that every set must reach momentary failure. The useful target depends on the exercise, goal, training phase, fatigue cost, safety, and the lifter.
Primary references
Journal of Strength and Conditioning Research, 2016. PMID: 26049792.
Strength and Conditioning Journal, 2016. PMID: 27531969.
Sports Medicine, 2022. PMID: 34542869.
Sports Medicine, 2023. PMID: 36334240.
Sports Medicine, 2024. PMID: 38970765.
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