Heart Rate Zone Calculator
Enter your age and resting heart rate to see your five training zones, using the Karvonen method. This is a general estimate for informational purposes only — not medical advice. Zones update as you type, and the link always reflects your numbers.
| Zone | Intensity | Target BPM range |
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How this calculator works
This tool uses the Karvonen method, which builds target heart rates from your Heart Rate Reserve rather than from max heart rate alone. First, estimated max heart rate is HRmax = 220 − age — a widely-used population-average formula with a real individual variance of roughly ±10–15 bpm; lab-based VO2 max testing is more precise if you need exact numbers. Heart Rate Reserve is HRR = HRmax − resting HR. The target heart rate at any intensity is then resting HR + HRR × (intensity ÷ 100). The five standard zones are Zone 1 "Very Light" (50–60% intensity), Zone 2 "Light / Fat Burn" (60–70%), Zone 3 "Moderate / Cardio" (70–80%), Zone 4 "Hard" (80–90%), and Zone 5 "Maximum" (90–100%).
Worked example
At age 35 with a resting heart rate of 65 bpm: HRmax = 220 − 35 = 185 bpm, and HRR = 185 − 65 = 120 bpm. That gives Zone 1: 125–137 bpm, Zone 2: 137–149 bpm, Zone 3: 149–161 bpm, Zone 4: 161–173 bpm, and Zone 5: 173–185 bpm. Notice each zone's upper bound is the next zone's lower bound — the ranges tile perfectly because they're all built from the same HRR.
Frequently asked questions
How accurate is the 220 − age formula for max heart rate?
It's a widely-used population-average estimate, not a measurement of you specifically — real individual variance is commonly cited at around ±10–15 beats per minute. Two people the same age can have genuinely different true max heart rates. Lab-based testing, such as a graded exercise test with VO2 max measurement, is meaningfully more precise if you need exact numbers for serious training or medical reasons. Treat the zones below as a solid general starting point, not a lab result.
Why does resting heart rate matter for this calculation?
The Karvonen method uses your resting heart rate to compute Heart Rate Reserve (HRR = max HR − resting HR), and builds every zone from that reserve instead of from max heart rate alone. This is a real advantage over simpler max-HR-only methods: two people with the same max heart rate but very different fitness levels usually have very different resting heart rates, and Karvonen's zones shift accordingly — a fitter person (typically a lower resting HR) gets a wider reserve and different target ranges than a less-conditioned person with the same max HR.
Which zone should I train in?
It depends on your goal, but the general framing behind each zone holds: Zone 1 (Very Light) suits easy recovery days; Zone 2 (Light / Fat Burn) is commonly used for building an aerobic base at a sustainable effort; Zone 3 (Moderate / Cardio) is a solid general cardio-fitness zone; Zones 4–5 (Hard to Maximum) are for high-intensity work and shouldn't dominate a weekly routine for most people. This is general, factual information, not personalized medical advice — if you have a heart condition or other health concerns, talk to a doctor before starting intense exercise.
How do I find my resting heart rate?
Count your pulse for a full 60 seconds right after waking up, before you get out of bed — that's when your heart rate is at its most stable baseline. Doing this for a few mornings in a row and averaging the results gives a more reliable number than a single reading, especially if you were unusually stressed, dehydrated, or under-slept on any one morning.
Is this medical advice?
No. This tool applies the published Karvonen formula to the numbers you enter and shows the result instantly in your browser — it is a general estimate for informational purposes only, not medical advice. It can't account for your individual cardiovascular health, medications, or fitness history. If you have a heart condition, are new to exercise, or have any health concerns, talk to a doctor before starting an intense training program.