Enter either your heart rate (BPM) during a steady, aerobic effort (for example, jogging, cycling, rowing) or your Borg RPE value (6–20) to estimate the other value using a common rule of thumb. This estimate is not intended for strength-training “RPE” (typically a 1–10 scale based on reps-in-reserve), where heart rate is a poor proxy for exertion.

RPE Calculator (Borg 6–20)

Enter exactly 1 value to estimate the other (rule of thumb: HR ≈ RPE × 10). This applies to the Borg 6–20 scale; if the estimate falls outside 6–20, the approximation likely isn’t applicable.

RPE Formula

This calculator estimates the relationship between exercise heart rate and the Borg Rating of Perceived Exertion (RPE) on the 6–20 scale. It is intended for steady aerobic exercise, where breathing, heart rate, and overall effort tend to rise together.

RPE \approx HR / 10

The same shortcut can be rearranged to estimate heart rate from a Borg RPE value:

HR \approx RPE \times 10
  • RPE = Borg perceived exertion score on the 6–20 scale
  • HR = heart rate during exercise in beats per minute (BPM)

Important: This calculator matches the Borg 6–20 endurance scale, not the common 1–10 lifting RPE scale. For strength training, heart rate is usually a poor proxy for set difficulty.

How to Interpret Borg RPE

RPE is a practical way to rate how hard exercise feels. Instead of relying only on a watch or monitor, it combines breathing rate, muscular fatigue, focus, and overall strain into a single number.

Borg RPE General Intensity Approx. HR (BPM) What It Usually Feels Like
6 Very, very light 60 Minimal effort, close to resting sensation
9 Very light 90 Easy warm-up pace
11 Light 110 Comfortable, relaxed, easy conversation
13 Somewhat hard 130 Steady training effort, noticeable breathing
15 Hard 150 Challenging but sustainable for a limited time
17 Very hard 170 Heavy breathing, difficult to maintain
19 Extremely hard 190 Near-maximal effort
20 Maximal 200 All-out exertion

The BPM values above are only the calculator’s rough conversion. Your actual heart rate can be higher or lower depending on fitness level, age, heat, fatigue, hydration, stress, medication use, and sensor accuracy.

How to Use the Calculator

  1. Choose a continuous aerobic activity such as jogging, cycling, rowing, brisk walking, or elliptical training.
  2. Hold a steady pace for several minutes so your effort is stable.
  3. Enter either your exercise heart rate or your Borg RPE score.
  4. Leave the other field blank so the calculator can estimate it.
  5. Compare the result to how the session actually feels before using it to guide training.

If the estimate falls outside the 6–20 Borg range, the shortcut likely does not fit that workout well.

Where This Calculator Is Most Useful

  • Steady-state cardio sessions
  • Base endurance training
  • Easy, moderate, and tempo pacing checks
  • Learning how perceived effort matches objective heart rate
  • Cross-checking whether a heart rate reading seems realistic for the effort

Common Training Anchors

Session Type Typical Borg RPE Feel Conversation Ability
Recovery / warm-up 8–10 Very easy Full sentences without effort
Easy endurance 11–12 Comfortable and controlled Easy conversation
Moderate aerobic work 13–14 Steady, purposeful effort Can still talk, but less freely
Tempo / threshold-like work 15–16 Hard and focused Short phrases only
Very hard effort 17–19 Severe discomfort, short duration Minimal talking possible

When the Estimate Becomes Less Reliable

The heart-rate-to-RPE shortcut works best when cardiovascular demand is the main driver of effort. It becomes less reliable when exercise is highly variable or when outside factors change either heart rate or perceived strain.

  • Intervals, sprints, circuits, and stop-and-go sports
  • Heavy strength training, powerlifting, and explosive lifting
  • Heat, humidity, altitude, dehydration, or poor sleep
  • Stress, anxiety, illness, or accumulated fatigue
  • Caffeine, stimulants, or medications that alter heart rate
  • Poor heart-rate sensor contact or inaccurate device readings

Borg RPE vs. Lifting RPE

System Scale Best For What It Reflects Use This Calculator?
Borg RPE 6–20 Endurance and aerobic exercise Overall exertion, breathing, cardiovascular strain Yes
Lifting RPE 1–10 Strength training How close a set is to failure, often tied to reps in reserve No

Examples

If your steady exercise heart rate is 140 BPM, the estimated Borg RPE is:

RPE \approx 140 / 10 = 14

If your effort feels like a 16 on the Borg scale, the estimated heart rate is:

HR \approx 16 \times 10 = 160

Practical Tips

  • Measure heart rate during the effort, not only after stopping.
  • Use the calculator after you have reached a stable rhythm rather than during the first minute or two of exercise.
  • Round to the nearest whole Borg number when needed, since perceived exertion is usually tracked as an integer.
  • Use both heart rate and RPE together for better pacing. Heart rate shows the workload; RPE shows how that workload feels on that specific day.
  • If the estimate and your actual sensation strongly disagree, trust the broader training context instead of forcing the numbers to match.

This calculator is best thought of as a quick endurance-training guide: simple, useful, and most accurate when your workout is steady, aerobic, and easy to interpret.