RPE and the Borg Scales (6–20 and CR10)
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Rating of Perceived Exertion lets you gauge intensity by how hard the effort feels — using either Borg's original 6–20 scale or the later 0–10 category-ratio (CR10) scale.
Detail
Rating of Perceived Exertion (RPE) is a subjective measure of how hard exercise feels, developed by Gunnar Borg. Two scales are in common use:
Borg 6–20 scale (original). Exertion is rated from 6 (no exertion) to 20 (maximal effort). The odd 6–20 range was chosen so that multiplying the rating by 10 roughly approximates the heart rate at that effort for a typical adult (e.g., an RPE of 13 ≈ 130 bpm). Its increase is fairly linear, tracking the proportional rise in physiological strain. Verbal anchors run from "very, very light" up through "somewhat hard" (≈13) and "hard" (≈15) to "very, very hard" (≈19–20).
Borg CR10 scale (category-ratio, ~1982). Exertion is rated from 0 (nothing at all / rest) to 10 (maximal). The CR10 is more logarithmic: at high intensities, small increases in effort feel disproportionately large, so the scale better reflects the subjective experience at the top end. Borg favored CR10 for clinical assessment of symptoms like breathlessness, chest pain/angina, and musculoskeletal pain.
Mapping to intensity (ACSM; see intensity-classification):
- Borg 6–20: moderate intensity ≈ 12–13 ("somewhat hard"); vigorous ≈ ≥14.
- CR10 (0–10): moderate ≈ 5–6; vigorous ≈ 7–8.
RPE is useful because it integrates all sources of strain (cardiovascular, metabolic, muscular, thermal) into one number, needs no equipment, and is valid even when heart rate is distorted (e.g., on medications affecting HR). It pairs naturally with the talk test (see talk-test) and supports autoregulated training (see autoregulation-rpe-rir).
Key facts
- Borg 6–20: rate 6 (none) to 20 (max); ×10 ≈ heart rate; roughly linear.
- Borg CR10: rate 0 (nothing) to 10 (max); more logarithmic; good for symptom rating.
- ACSM mapping — 6–20: moderate 12–13, vigorous ≥14. CR10: moderate 5–6, vigorous 7–8.
- No equipment needed; integrates all sources of strain; valid when HR is unreliable.
Connections
- intensity-classification — the RPE-to-intensity mapping.
- talk-test — a simpler companion subjective gauge.
- heart-rate-zones — RPE cross-checks HR-based zones.
- autoregulation-rpe-rir — adjusting load by perceived effort.
Educational content only — not medical advice. Always consult a qualified professional for individualized guidance, especially around injury, pregnancy, or medical conditions.