RPE in strength training: the scale and RIR explained

What RPE means in different contexts

Perceived-exertion scales describe how demanding an effort feels. The number only makes sense with its scale and context. Borg’s 6–20 scale, a 0–10 effort scale and the RIR-based strength scale cannot be substituted without explanation.

For a strength set, repetitions in reserve (RIR) estimates how many more repetitions could have been completed using the same range, technique and pace criteria. The RIR-based RPE scale gives that estimate a number. A set stopped by a lost grip or changed technique needs that context in the log.

The Zourdos study examined this scale and bar velocity during squat testing in experienced and novice participants. It supported a relationship under those conditions, not proof that every trainee rates effort exactly or that RPE-based programming outperforms all alternatives.

A practical RPE table for strength sets

The upper part of the RIR-based scale has the clearest repetition anchors. Lower ratings and half points are less precise descriptions, not measurements of a fraction of a repetition.

RPE and RIR: related, with limits

Near the upper anchors, RPE is commonly described as 10 minus estimated RIR: for example, 2 RIR corresponds to RPE 8. This shortcut should not be extended as an exact arithmetic law across every low rating or other effort scale.

A bench-press study in 24 trained adults found small average errors when participants predicted one or three remaining repetitions at 75% of their maximum. That average is not a guarantee that every set or person is accurate to within one repetition. It does not directly describe beginners, very long sets or another exercise.

Keep the same definition of a valid repetition. Changing tempo, range, assistance or equipment changes what remains possible. A high discomfort or breathlessness rating is not automatically the same as having few repetitions left.

How to use a target such as 3 × 6 at RPE 8

This example means three sets of six repetitions, choosing a load expected to leave about two further valid repetitions after each set. It does not mean using 80% of maximum, and the same load may produce different ratings across sets.

1. Prepare with relevant lighter practice and ramp-up sets. Use a load estimate based on recent comparable work.
2. Complete the planned repetitions, stopping if the intended technique or control changes substantially.
3. Record the set RPE promptly with load, repetitions and any setup changes.
4. If effort differs from the target, consider a manageable adjustment for the next set, allowing for rest, fatigue and the exercise. Do not automatically add weight after one unexpectedly easy set.
5. Compare several sessions under similar conditions before treating a lower rating as proof of a lasting strength gain.

Learning the rating without turning every set into a test

Use conservative loads while learning, and record uncertainty when unsure. Coaching feedback, video of repeatable technique and a consistent log can help. A set taken to failure is not a requirement for calibration, especially alone under a bar.

RPE 7–9 is one common working range, with lower effort for practice and demanding compound work. These are coaching choices to adapt, not a universal prescription or a reason to take every machine set to failure. Machines also require a suitable stop and exit method.

The older-women training study used a 6–20 perceived-effort scale. It did not compare RIR-based RPE against percentage-based programming or establish the superiority of one prescription method. Keep that distinction when applying its findings.

A percentage of maximum and an effort target can provide different information. Neither removes the need to manage total volume, skill, recovery and a safe training setup.

Whole-session RPE is a different record

Session RPE rates the whole workout rather than the final repetitions of one set. In one monitoring method, the session rating on its specified scale is multiplied by duration in minutes to create an arbitrary-unit load estimate. Use consistent timing and instructions if comparing it over time.

The Foster study compared session-RPE monitoring with a heart-rate method in cycling and basketball. It did not directly validate RIR estimates in lifting, establish performance gains or turn the session score into a diagnosis. Do not convert a session rating into repetitions in reserve.

Keep set records and session records clearly labelled. A difficult set can sit inside an easy overall session, and a long session can feel demanding without every set being close to failure.

Make the log useful

Record the exercise, load, repetitions, RPE, range and relevant setup. Use the same scale and repetition criteria next time. Note a major change in sleep, symptoms or session organisation as context without treating the score as a clinical measurement.

For practice on specific lifts, see the barbell squat, bench press and seated leg curl. The warm-up guide explains preparation before the work sets.

If an exercise or prescription causes concerning symptoms, adapt and seek individual advice rather than using an effort number to override them.