Training effort reference
RPE vs. RIR: two ways to record how hard a set felt
Learn the relationship between RPE and reps in reserve, how to log effort, and why estimates become more useful with practice.
The short answer
RIR estimates how many good reps remained at the end of a set. RPE rates the set’s difficulty; in the common lifting scale, RPE 10 is about 0 RIR, RPE 9 is about 1 RIR, and RPE 8 is about 2 RIR. Both are estimates, not laboratory measurements.
Teach the coach your effort
Make “hard” useful over time.
When you log RPE, RIR, or a plain-language effort note, LogFast can compare similar work and reason about progression with more than weight alone.
Track effort with LogFastThe simple conversion
For resistance training, a practical relationship is RIR = 10 − RPE. Half steps describe uncertainty or a set between two anchors. RPE 8.5 suggests roughly one to two reps remained.
This is different from the original Borg 6–20 cardiovascular exertion scale. Always clarify which RPE scale your program uses.
- RPE 10 ≈ 0 RIR
- RPE 9 ≈ 1 RIR
- RPE 8 ≈ 2 RIR
- RPE 7 ≈ 3 RIR
Why effort belongs beside load and reps
A set of eight at the same weight can represent different training stress on different days. Adding RPE or RIR helps explain whether performance was comfortable, near the limit, or affected by fatigue.
Effort is especially useful when a program autoregulates load. Instead of forcing a fixed number, you choose a load that produces the target reps at the target RIR.
Accuracy improves with calibration
Research suggests RIR can be reliable for load prescription, but people are not perfectly accurate. Estimates tend to be less accurate with lighter loads and higher repetitions, and experience can help.
Calibrate occasionally by completing a safe set to technical failure when appropriate, ideally on a lower-risk exercise. Compare the reps you predicted with the reps you actually completed. Do not turn every session into a test.
How to log RPE or RIR
Log the value immediately after the set, before the feeling is rewritten by the next set. Use one scale consistently. A note like “8 reps at 135, RPE 8” is more useful than changing between RPE, difficulty adjectives, and emojis.
Treat the value as one signal. Technique, pain, speed, sleep, and exercise order still matter.
Frequently asked questions
Is RPE 8 the same as 2 RIR?
Approximately, on the common 1–10 resistance-training RPE scale. Individual estimates vary.
Should beginners use RPE?
Beginners can use it, but should expect calibration errors. Simple anchors such as easy, challenging, and near-failure may be enough initially.
Is RIR accurate for high-rep sets?
It is generally harder to estimate at lighter loads and higher reps. Use wider confidence and avoid treating the estimate as exact.