Target Heart Rate Formula (Karvonen Method)
Calculate your target heart rate zone using the Karvonen formula.
Optimise exercise intensity with THR = ((Max HR - Resting HR) × %Intensity) + Resting HR.
The Formulas
The Karvonen method calculates your target heart rate based on both your maximum and resting heart rates.
This gives a more personalised training zone than using maximum heart rate alone.
Variables
| Symbol | Meaning |
|---|---|
| THR | Target Heart Rate (beats per minute, bpm) |
| Max HR | Maximum Heart Rate (bpm) |
| Resting HR | Resting Heart Rate (bpm) — measured when fully at rest |
| %Intensity | Desired exercise intensity as a decimal (e.g., 0.70 for 70%) |
| age | Age in years |
Training Zones
| Zone | Intensity | Purpose |
|---|---|---|
| Warm-up | 50-60% | Light activity, recovery |
| Fat Burning | 60-70% | Aerobic endurance, fat utilisation |
| Cardio | 70-80% | Cardiovascular fitness |
| Hard Training | 80-90% | Performance improvement |
| Maximum | 90-100% | Short bursts, competitive effort |
Example 1
A 35-year-old with a resting heart rate of 65 bpm wants to train at 70% intensity. What is the target heart rate?
Max HR = 220 - 35 = 185 bpm
THR = ((185 - 65) × 0.70) + 65
THR = (120 × 0.70) + 65
THR = 84 + 65
THR = 149 bpm
Example 2
A 50-year-old with a resting heart rate of 72 bpm wants to find their 60-80% training zone.
Max HR = 220 - 50 = 170 bpm
Heart Rate Reserve = 170 - 72 = 98 bpm
Lower bound (60%): (98 × 0.60) + 72 = 58.8 + 72 = 130.8 bpm
Upper bound (80%): (98 × 0.80) + 72 = 78.4 + 72 = 150.4 bpm
Target zone: 131 - 150 bpm
When to Use It
Use the target heart rate formula when you need to:
- Set safe and effective exercise intensity levels
- Monitor cardio workouts for optimal training benefit
- Design heart rate-based training programmes
- Gradually increase exercise intensity over time
The "220 - age" estimate for maximum heart rate is an approximation.
Individual maximum heart rates can vary by 10-20 bpm from this estimate.
This formula is for general educational purposes only. It is not medical advice. Consult a healthcare professional before starting a new exercise programme, especially if you have any heart conditions.