Exercise Prescription · Cardiac Rehab · Pulmonary Rehab · Borg 1982

Borg RPE Scale Calculator

Rating of Perceived Exertion — Original 6–20 scale and Modified CR10 (0–10) with estimated heart rate, exercise intensity zone, and clinical target RPE for cardiac rehabilitation, COPD, pulmonary rehab, and physical therapy exercise prescription.

Clinically reviewed by Dr. Nikhil Mahajan, PT, MPT  ·  Jan 15, 2026
6 – 20 Original Scale Heart rate correlation
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0 – 10 Modified CR10 Dyspnoea / breathlessness
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× 10 Est. Heart Rate RPE × 10 ≈ bpm
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12 – 16 ACSM Target Moderate–Vigorous zone
Scale 6–20
RPE Selected —
Est. Heart Rate —
Zone —
Scale Version
years
Select RPE (6–20 Scale)

Progress Tracker Optional

Enter a previous RPE score to track intensity progression between sessions

Borg 6–20 Scale — Score Reference Table

RPE Verbal Descriptor Est. HR (bpm) Zone Clinical Use
6 No exertion at all ~60 Rest Resting baseline
7 Extremely light ~70 Very Light Very gentle warm-up
8 Extremely light ~80 Very Light Warm-up / cool-down
9 Very light ~90 Light Active recovery
10 Very light ~100 Light Deconditioned patients
11 Light ~110 Light Phase 1 cardiac rehab, early post-op
12 ★ Light ~120 Moderate ACSM moderate zone begins
13 ★ Somewhat hard ~130 Moderate Target: most PT patients, COPD
14 ★ Somewhat hard ~140 Moderate–Hard Upper moderate zone
15 ★ Hard (heavy) ~150 Hard Vigorous — healthy adults
16 ★ Hard (heavy) ~160 Hard Cardiac HIIT lower bound
17 Very hard ~170 Very Hard Phase 2 HIIT (85–95% HRpeak)
18 Very hard ~180 Very Hard High-intensity athletes
19 Extremely hard ~190 Maximal Near-max — testing only
20 Maximum exertion ~200 Maximum VO₂max testing only

Modified Borg CR10 Scale — Reference Table

CR10 Verbal Descriptor Zone Clinical Application
0 Nothing at all Rest Resting baseline — no breathlessness
0.5 Very, very weak Very Light Minimal exertion, breathing exercises
1 Very weak Very Light Gentle walking, early mobilisation
2 Weak (light) Light Phase 1 post-operative rehab
3 ★ Moderate Moderate COPD / pulmonary rehab target
4 ★ Somewhat strong Moderate Upper limit high-risk cardiac
5 ★ Strong (heavy) Hard Upper safety limit — clinical populations
6 Strong Hard Vigorous — healthy supervised adults
7 Very strong Very Hard High intensity — trained individuals
8 Very strong Very Hard Near-maximum effort
9 Very, very strong Near Max Approach to absolute maximum
10 Extremely strong (Maximum) Maximum Absolute max — VO₂max / sprint testing

Target RPE by Clinical Population

Population Target RPE (6–20) Target CR10 Notes
Healthy adults — moderate 12–14 3–4 ACSM recommendation for general fitness
Healthy adults — vigorous 15–17 5–7 ACSM vigorous intensity zone
Cardiac rehab — Phase 1 (inpatient) 11–13 2–3 Conservative — monitor for symptoms throughout
Cardiac rehab — Phase 2 (outpatient) 12–16 3–5 HIIT: RPE 16–17 = 85–95% HRpeak (AACVPR)
COPD / Pulmonary rehabilitation 12–14 3–4 CR10 preferred for dyspnoea quantification
Post-surgical early mobilisation 10–12 2–3 Safe range for acute post-op period
Elderly / Deconditioned 11–13 2–3 Fall risk increases above RPE 14 in frail elderly
Beta-blocker patients 11–14 3–4 RPE essential — HR blunted by medication

What Is the Borg RPE Scale?

The Borg RPE Scale (Rating of Perceived Exertion) is a standardised clinical tool developed by Swedish psychologist Gunnar Borg in the 1960s and formally published in Medicine & Science in Sports & Exercise in 1982 (PMID: 7127900). It quantifies a patient's subjective perception of exercise intensity — integrating breathlessness, muscle fatigue, heart rate, and overall effort into a single numerical rating used globally in exercise prescription, cardiac rehabilitation, pulmonary rehabilitation, and research.

Why the Borg Scale Starts at 6

Gunnar Borg deliberately designed the 6–20 range so that multiplying by 10 approximates resting heart rate (~60 bpm = RPE 6) through to maximum heart rate (~200 bpm = RPE 20) for a healthy young adult. This makes the Borg 6–20 scale an indirect heart rate estimator — particularly valuable for patients on beta-blockers where pharmacological blunting of the heart rate response to exercise makes direct HR-based exercise prescription unreliable.

Borg 6–20 vs Modified CR10 — When to Use Which

The original 6–20 scale was designed for aerobic/cardiovascular exercise prescription and correlates linearly with heart rate. It is endorsed by ACSM, AACVPR, and AHA for cardiac rehabilitation and graded exercise testing. The Modified CR10 scale (0–10) was developed by Borg in 1982 specifically for quantifying symptoms — dyspnoea, breathlessness, and musculoskeletal pain — and is the AACVPR-preferred dyspnoea scale for pulmonary rehabilitation and COPD management.

How to Administer the Borg RPE Scale

  • Show the full scale before exercise begins — not during. Allow the patient to read all anchors. Ensure they understand 6 = no exertion at all, 20 = absolute maximum imaginable.
  • Ask about overall body exertion — "Rate how hard your whole body feels right now — your breathing, muscles, and fatigue together."
  • Never suggest a number — this biases the response. Simply ask: "What number on the scale best describes how you feel right now?"

Reliability and Validity

The Borg 6–20 scale has strong test-retest reliability (ICC = 0.85–0.96) and has been validated against heart rate, VO₂, blood lactate, and ventilation across multiple clinical populations. Chen et al. (2002) meta-analysis confirmed criterion-related validity (r = 0.62 with VO₂, r = 0.80 with HR) across 18 studies. The Modified CR10 demonstrates strong validity for dyspnoea in COPD and has been adopted by AACVPR as the preferred dyspnoea scale in pulmonary rehabilitation.

Clinical Applications

  • Cardiac rehabilitation — Primary intensity prescription tool for beta-blocker patients; target RPE 11–14 moderate phase, RPE 16–17 for HIIT (AACVPR)
  • COPD and pulmonary rehab — CR10 for dyspnoea monitoring; reduce intensity if CR10 reaches 5 in high-risk patients
  • Post-surgical mobilisation — RPE 10–12 for Phase 1 early ambulation, progressing as tolerated
  • Graded exercise testing (GXT) — Serial RPE at each workload stage to assess perceived effort at VO₂max
  • Exercise prescription without HR monitor — Valid substitute for heart rate monitoring in patients with pacemakers, arrhythmias, or beta-blockade
Dr. Nikhil Mahajan, PT, MPT Doctor of Physical Therapy · Reviewed January 15, 2026 · View full credentials

Frequently Asked Questions

Why does the Borg RPE scale start at 6 instead of 0?
Gunnar Borg deliberately started at 6 so that multiplying by 10 approximates resting heart rate (~60 bpm) in a healthy young adult. The scale ends at 20 to correspond with an approximate maximum heart rate of 200 bpm. This design makes the Borg scale an indirect heart rate estimator during aerobic exercise — especially valuable in beta-blocker patients where measured heart rate cannot reliably guide exercise prescription.
What is the difference between Borg 6-20 and Modified CR10?
The original 6–20 scale was designed for aerobic exercise prescription and correlates linearly with heart rate (score × 10 ≈ HR in bpm). The Modified CR10 (0–10) was designed for quantifying symptoms like dyspnoea, breathlessness, and musculoskeletal pain — preferred in pulmonary rehabilitation and COPD management. CR10 score 5 is the upper safety limit for most clinical populations.
What RPE should I target for moderate intensity exercise?
On the 6–20 scale, moderate intensity is RPE 12–14 (Somewhat Hard), corresponding to approximately 50–70% of maximum heart rate. On CR10, moderate is 3–4. ACSM Guidelines for Exercise Testing and Prescription (11th edition, 2021) recommend RPE 12–16 for most adults during health-promoting aerobic exercise. For most PT patients, RPE 13 is the sweet spot — noticeable effort but still comfortable enough for conversation.
Can Borg RPE replace heart rate monitoring in cardiac rehabilitation?
Yes — and in many cases it is preferable. Beta-blockers blunt the heart rate response to exercise, making target HR zones unreliable. RPE is entirely unaffected by beta-blockade. In Phase 2 cardiac rehabilitation, RPE 12–14 is the AACVPR standard target for moderate-intensity sessions. For HIIT in Phase 2, RPE 16–17 corresponds to 85–95% HRpeak. RPE should be used alongside — not exclusively instead of — physiological monitoring where possible.