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Borg RPE Scale Calculator

Enter your Borg RPE rating to estimate heart rate and effort.

How it is calculated

You enter one rating on the 6 to 20 Borg scale (decimals such as 13.5 are accepted; values outside 6 to 20 give no result). Estimated heart rate is HR = RPE × 10 beats per minute. Effort percentage rescales the scale so 6 is 0% and 20 is 100%: effort = (RPE − 6) / 14 × 100. The category comes from fixed cut-offs: below 9 Very light, 9 to under 11 Light, 11 to under 14 Moderate, 14 to under 17 Hard, 17 to under 19 Very hard, and 19 or more Maximal. The heart rate is a rule-of-thumb figure for a typical adult, not a measurement of your own pulse.

Worked example

You rate a tempo run as 15. Estimated heart rate: 15 × 10 = 150 bpm. Effort: (15 − 6) / 14 × 100 = 9 / 14 × 100 = 64.29%. The rating falls in the 14 to under 17 band, so the category is Hard. A rating of 13 would give 130 bpm, 50.00% and Moderate.

Try this example →

Common mistakes

  • Using the 0 to 10 category-ratio scale. This tool is the original 6 to 20 scale, so a rating of 5 or lower gives no result.
  • Treating the heart rate as exact. It is simply RPE × 10, and age, fitness, heat or medication can put your real pulse well away from it.
  • Reading the effort percentage as a percentage of maximum heart rate. It only rescales the 6 to 20 scale to 0 to 100%, so RPE 13 is 50% effort but not 50% of max HR.
  • Rating how tired you are in general rather than how hard the current exercise feels. The score should reflect breathing, muscle strain and effort at that moment.
  • Entering the rating after you have rested. The score is meant to describe effort during the exercise, so a score given at rest describes a different moment.

Sources

About this calculator

The Borg Rating of Perceived Exertion (RPE) scale, developed by Swedish psychologist Gunnar Borg, is a 6-to-20 scale that lets someone rate how hard they feel their body is working during exercise, based on physical sensations like breathing rate, muscle fatigue, and sweating rather than a heart rate monitor. The scale's odd 6–20 range wasn't arbitrary — it was designed so that multiplying the RPE value by 10 gives a rough estimate of heart rate in beats per minute for a typical adult during steady-state exercise.

This calculator takes an RPE rating and returns the estimated heart rate, an effort percentage, and an intensity category, following the original Borg design logic. It's widely used in exercise physiology, cardiac rehabilitation, and personal training as a low-cost, equipment-free way to gauge and prescribe exercise intensity — particularly valuable for people on heart-rate-altering medications like beta blockers, where a heart rate monitor alone can be misleading.

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