The Borg RPE scale runs from 6 (rest) to 20 (maximal effort), designed so that the number multiplied by 10 approximately corresponds to heart rate. A rating of 12-13 (‘somewhat hard’) corresponds to approximately 120-130 bpm. The scale preceded modern zone systems and is still widely used in clinical and research settings. A 6-20 scale is Borg’s original; his modified CR10 scale (0-10) is more widely used in practical fitness settings as the simpler alternative. Both versions are well-validated against physiological markers of exercise intensity.
Key points
- Scale: 6 (rest) to 20 (maximal)
- Rating × 10 ≈ heart rate
- 12-13 = moderate; 17-18 = very hard
- Modified CR10 (0-10) is more commonly used today
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