HEART RATE ZONE CALCULATOR
Calculate your personalized heart rate training zones using the Karvonen formula. Enter your resting heart rate and maximum heart rate to determine your target heart rate zones for different training intensities. These zones help optimize your workouts by ensuring you train at the right intensity for your specific fitness goals.
Heart Rate Zone Calculator (Karvonen Formula)
This calculator uses the Karvonen formula to estimate your personalized heart rate zones based on both your maximum heart rate (MHR) and your resting heart rate (RHR). By including resting heart rate, it provides a more accurate reflection of your fitness level than the basic percentage of max heart rate method.
How the Karvonen Formula Works
The Karvonen method calculates your target heart rate by applying training intensity to your heart rate reserve (HRR), which is the difference between your maximum and resting heart rate.
Formula:
Target HR = ((Max HR − Resting HR) × %Intensity) + Resting HR
Once you enter your MHR and RHR, the calculator determines your training zones using these intensity ranges:
| Zone | Purpose | Intensity |
|---|---|---|
| Zone 1 | Active recovery / very light | 50–60% |
| Zone 2 | Aerobic base / easy effort | 60–70% |
| Zone 3 | Tempo / moderate | 70–80% |
| Zone 4 | Threshold / hard | 80–90% |
| Zone 5 | VO₂ max / very hard | 90–100% |
For example, with a Max HR of 190 bpm and a Resting HR of 70 bpm:
Heart Rate Reserve = 190 − 70 = 120 bpm.
At 60% intensity → (120 × 0.6) + 70 = 142 bpm.
At 70% intensity → (120 × 0.7) + 70 = 154 bpm.
So Zone 2 is roughly 142–154 bpm.
Verify Your Zones With Effort
These formulas give a strong base, but always match them with how you feel. Use the Rate of Perceived Exertion (RPE) or talk test as a guide:
- Zone 1: You can sing comfortably.
- Zone 2: You can talk easily – steady, easy effort.
- Zone 3: Short sentences only – moderate effort.
- Zone 4: Talking is hard – high effort.
- Zone 5: Only a few words – all-out effort.
For More Context
This calculator is based on concepts explained in the article “You Might Be Training In the Wrong Heart Rate Zones” by Quentin van Bentum. That piece dives deeper into the difference between heart rate methods, how to estimate your maximum heart rate, and why the Karvonen approach often gives better results.
This section is made to support the calculator and help you understand how it works, not to replace the main article. For a full explanation, check the reference above.
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Frequently Asked Questions
Common questions about using the heart rate zone calculator and Karvonen formula.
The Karvonen formula calculates target heart rate zones using your heart rate reserve (HRR), which is the difference between your maximum heart rate and resting heart rate. The formula is: Target HR = ((Max HR - Resting HR) × %Intensity) + Resting HR. This method is more accurate than using simple percentages of maximum heart rate because it accounts for your individual fitness level through your resting heart rate.
To find your maximum heart rate, you can perform a maximum effort test (with medical clearance) or use the age-based formula: 208 - (0.7 × age). Your resting heart rate should be measured first thing in the morning while still in bed, before any activity. Take your pulse for a full minute on multiple mornings and average the results. The calculator can estimate both values if you provide your age and activity level.
The five heart rate zones are: Zone 1 (Recovery) at 50-60% of HRR for easy recovery runs, Zone 2 (Endurance) at 60-70% for building aerobic base, Zone 3 (Tempo) at 70-80% for moderate-intensity training, Zone 4 (Threshold) at 80-90% for improving lactate threshold, and Zone 5 (Maximum) at 90-100% for high-intensity intervals. Each zone targets different physiological adaptations and training goals.
Yes, the calculator can estimate your maximum heart rate using your age (208 - 0.7 × age) and your resting heart rate based on your activity level (sedentary: ~70 bpm, moderately active: ~60 bpm, very active: ~50 bpm, elite: ~40 bpm). However, measured values are more accurate and will provide more precise training zones. If possible, measure your actual resting heart rate for best results.
Your heart rate zones should be recalculated as your fitness improves, typically every 4-6 weeks or after significant training periods. As you become more fit, your resting heart rate typically decreases, which will shift your zones. You should also recalculate if your maximum heart rate changes (which can decrease slightly with age) or if you've had a significant change in fitness level or training status.