What Is the Karvonen Formula?
The Karvonen formula is one of the most accurate methods for calculating your target heart rate (THR) during exercise. Unlike the simple percentage-of-maximum-heart-rate method, the Karvonen approach accounts for your resting heart rate (RHR), making it personalized and physiologically meaningful.
The formula was developed by Finnish physiologist Martti Karvonen in the 1950s and remains widely used by coaches, athletes, and healthcare professionals today.
Why Do We Need the Target Heart Rate?
Exercise intensity matters enormously for achieving your fitness goals. Training too lightly won't produce meaningful cardiovascular improvements, while training too hard risks injury and overtraining.
Organizations including the CDC, American Heart Association, Mayo Clinic, and the U.S. Department of Health and Human Services recommend at least 150 minutes of moderate-intensity aerobic activity per week (or 75 minutes of vigorous activity).
Moderate intensity is generally defined as 50–70% of your maximum heart rate — but the Karvonen method gives you a more precise target based on your individual fitness level.
How to Calculate Target Heart Rate Using the Karvonen Formula
The Karvonen formula for Target Heart Rate (THR) requires three values:
- MHR — Maximum Heart Rate (bpm). If unknown, estimate it as
220 − Age. - RHR — Resting Heart Rate (bpm). Measure it in the morning before getting up.
- Intensity — the desired exercise intensity as a percentage (e.g., 60%).
The equation is:
THR = ((MHR − RHR) × Intensity) + RHR
The term (MHR − RHR) is called the Heart Rate Reserve (HRR) — it represents the range your heart can operate within during exertion.
How to Calculate Maximum Heart Rate Using the Karvonen Formula
The standard Karvonen estimate for Maximum Heart Rate is:
MHR = 220 − Age
For example, a 35-year-old person has an estimated MHR of 185 bpm.
If you know your actual MHR from a stress test or laboratory measurement, you can enter it manually in this calculator for even greater accuracy.
Heart Rate Zones (Karvonen Method)
| Zone | Intensity | Goal / Benefit |
|---|---|---|
| Light / Warm Up | 50–60% | Recovery, warm-up, beginners |
| Moderate / Fat Burn | 60–70% | Fat burning, general fitness |
| Aerobic / Endurance | 70–80% | Cardiovascular fitness, endurance |
| Anaerobic / Performance | 80–90% | Speed, power, lactate threshold |
| Maximum / VO₂ Max | 90–100% | Peak performance, short bursts only |
How to Use This Karvonen Formula Calculator
- Enter your age in years.
- Enter your resting heart rate (RHR) in bpm. Measure it in the morning while still lying in bed for best accuracy.
- Optionally enter your maximum heart rate manually (e.g., from a stress test). Otherwise, the calculator uses
220 − Age. - Set the intensity range you want to train at (e.g., 60–70% for moderate exercise or fat burning).
- Click Calculate to get your personalized target heart rate range and all five training zones.
FAQs
How do I calculate my Heart Rate Reserve?
Heart Rate Reserve (HRR) is simply:
HRR = Maximum Heart Rate − Resting Heart Rate
For example: MHR = 185 bpm, RHR = 65 bpm → HRR = 120 bpm.
What is moderate exercise according to the Karvonen formula?
Moderate exercise is typically 50–70% of MHR using the simple method, but with the Karvonen formula the equivalent zone is also often quoted as 50–70% of HRR + RHR. The Karvonen result will be somewhat higher than the simple % of MHR because it accounts for your resting heart rate.
Why is the Karvonen result different from % of MHR?
The simple "% of MHR" method does not account for your fitness level. A highly trained athlete with a resting HR of 45 bpm and an untrained person with 80 bpm would get the same target — which is inaccurate. The Karvonen formula corrects for this using HRR.
Is this calculator medically approved?
This tool is for informational and educational purposes only. Always consult a qualified healthcare professional before starting a new exercise program, especially if you have any cardiovascular condition.