Target Heart Rate Calculator (Karvonen Formula)
＋More features: 5-zone table and a mid-workout pulse check
Five zones by purpose (based on maximum heart rate)
Lists the five zones as percentages of maximum heart rate (220 − age) — the same idea smartwatches use.
Check your intensity from a pulse you just took
Pause your workout, count your wrist pulse for 10 seconds and enter it to see your current exercise intensity (the age field above is used).
Just enter your age and resting heart rate to find the heart rate that is right for fat burning. It lists the target heart rate for each intensity level. Use it when you want to know how hard to push during walking or exercise-bike sessions.
How to use
- Enter your age.
- Enter your resting heart rate (most accurate right after waking up, before getting out of bed: count your wrist pulse for one minute).
- As you type, the target heart-rate zones for 40–70% intensity are shown automatically.
How it is calculated
- Estimated maximum heart rate = 220 − age (a widely used estimate)
- Target heart rate = (maximum heart rate − resting heart rate) × intensity % + resting heart rate (Karvonen formula)
- Example: 40 years old, resting 70, at 50% intensity → (180−70)×0.5+70 = 125 bpm
- Intensity guide: 40–60% = general health and fat burning (easy to somewhat hard) / 60–70% = endurance building (somewhat hard)
Sources (primary information)
- The Karvonen formula and exercise intensity: Ministry of Health, Labour and Welfare (Japan), e-Health Net — Physical activity and exercise (in Japanese)
Assumptions and notes
- “220 − age” is an estimate; actual maximum heart rate varies between individuals (by ±10 bpm or more).
- If you are being treated for heart disease, high blood pressure or similar, or take medication that affects heart rate (such as beta blockers), always consult a doctor before choosing an exercise intensity.
- Stop exercising immediately if you feel chest pain, severe shortness of breath or dizziness.
Frequently asked questions
I heard gentle exercise is better for burning fat. Is that true?
At 40–60% intensity, a higher share of the energy you burn comes from fat, and the pace is easier to keep up. Total calories burned still rise with intensity, so the basic rule is “an intensity you can sustain, for longer”.
I do not know my resting heart rate.
In the morning, before getting out of bed, place the fingers of one hand on the thumb side of the other wrist and count for one minute. A smartwatch's sleeping heart rate also works. A typical adult range is 60–80 bpm.
How do I measure my heart rate during exercise?
A smartwatch or a chest-strap heart-rate monitor is convenient. Without a device, you can pause briefly, count your pulse for 10 seconds and multiply by 6.