Formula & Calculator
Target Heart Rate (Karvonen Formula)
Calculates a personalized training heart rate using both maximum and resting heart rate for a chosen exercise intensity.
Interpretation
THR = ((HRmax − HRrest) × intensity) + HRrest. Uses heart rate reserve to set exercise intensity. More individualised than percentage of HRmax alone.
Variables
| Symbol | Quantity | Unit |
|---|---|---|
| THR | Target heart rate | bpm |
| HRmax | Maximum heart rate | bpm |
| HRrest | Resting heart rate | bpm |
| intensity | Desired intensity (0 to 1) |
What it means
The Karvonen formula calculates target heart rate (THR) for exercise by incorporating resting heart rate (HRrest). It uses the heart rate reserve (HRmax − HRrest) multiplied by desired intensity, then adds HRrest. This accounts for individual fitness and provides a more accurate training zone than a simple percentage of HRmax. It is widely used in cardiopulmonary rehabilitation, athletic training, and fitness programming. For example, an intensity of 60‑80% is common for aerobic conditioning. Understanding this formula helps in prescribing safe and effective exercise loads tailored to an individual’s fitness level.
Worked example
Target Heart Rate (Karvonen) – Two Detailed Examples
Real‑World| Parameter | Value |
|---|---|
| HRmax (bpm) | 180 |
| HRrest (bpm) | 60 |
| intensity | 0.70 |
| Parameter | Value |
|---|---|
| HRmax | 170 |
| HRrest | 70 |
| intensity | 0.60 |
Common mistakes
- Karvonen formula: THR = ((HRmax − HRrest) × intensity) + HRrest – uses heart rate reserve.
- Intensity: Typically 0.5‑0.85 (50‑85% of heart rate reserve).
- HRrest: Resting heart rate – measure when fully rested, preferably in the morning.
- Target zone: Used to prescribe exercise intensity – more accurate than percentage of HRmax alone.
- Medications: Beta‑blockers lower HR – the formula may not apply.
Applications
The Karvonen formula calculates target heart rate (THR) by incorporating the resting heart rate (HRrest) and desired exercise intensity (as a percentage of heart rate reserve). This provides a more personalised and accurate target than simply using a percentage of HRmax. Exercise physiologists, trainers, and cardiac rehabilitation specialists use it to prescribe individualised exercise intensities. By using THR, individuals can optimise cardiovascular benefits while minimising risks. This formula is essential for designing interval training, for tracking fitness improvements (as resting heart rate decreases), and for ensuring that exercise is safe and effective. It is a core tool in clinical and fitness exercise prescription.
- Individualised exercise intensity programming
- Cardiac rehabilitation and post‑infarction exercise
- Fitness assessment and improvement tracking
- Sports training – heart rate zone determination
- Health and wellness coaching
Frequently Asked Questions
It calculates a personalised exercise heart rate using both maximum and resting heart rates: THR = ((HRmax − HRrest) × intensity) + HRrest.
HRmax = estimated maximum heart rate (220 − age)
HRrest = resting heart rate (measured first thing in the morning)
intensity = desired fraction (e.g., 0.6 for 60%)
It accounts for individual fitness by using the heart rate reserve (HRmax − HRrest). This makes the target more personalised than using a percentage of HRmax alone.
- Moderate exercise: 40–59%
- Vigorous exercise: 60–84%
- High intensity: 85–95%
A 30‑year‑old with HRrest = 60 bpm. HRmax = 190. For 70% intensity: THR = (190−60)×0.70 + 60 = 130×0.70 + 60 = 91 + 60 = 151 bpm.
Simple method: THR = HRmax × intensity. For the same person at 70%: 190×0.70 = 133 bpm. Karvonen gives 151 bpm, which is higher and more accurate for fitter individuals.
- Forgetting to measure resting heart rate accurately (use a relaxed morning measurement).
- Using the formula with an inaccurate HRmax (use the Tanaka or tested value).
- Applying the same intensity for all activities without considering perceived exertion.
It is suitable for healthy adults. For those on beta‑blockers or with heart conditions, an exercise test with ECG is recommended.
Using a heart rate monitor (chest strap or optical sensor) or by taking pulse manually for 15 seconds and multiplying by 4.
It ensures you are exercising at the correct intensity to improve cardiovascular fitness without overexertion.