Fitness calculator
Heart Rate Zone Calculator
Calculate five training heart-rate zones from your age and resting heart rate with the Karvonen method.
Max heart rate
187 bpm
How it works
Maximum heart rate (MHR) is the upper limit of what your cardiovascular system can handle during intense exercise. The Tanaka formula (208 − 0.7 × age) is more accurate for adults than the classic formula (220 − age), but both have individual variation of ±10–12 bpm. If you know your measured max from a stress test or high-intensity training, use that instead.
The Karvonen method uses your heart-rate reserve (MHR minus resting HR) and places the zones at percentages of that reserve rather than of MHR itself. That personalizes the zones: a runner with a low resting heart rate has a larger reserve and wider zones. If you leave resting heart rate blank, the calculator falls back to straight percentages of MHR.
Resting heart rate should be measured first thing in the morning, before getting out of bed, over several days for an average.
The Karvonen method also tracks your fitness over time. As you get fitter your resting heart rate drops, your reserve grows, and your zone boundaries shift upward to match.
The five training zones
- Zone 1 (Very light, 50–60%): Recovery training. Easy, conversational pace. Ideal for active recovery days.
- Zone 2 (Light, 60–70%): Aerobic base building. Fat-burning zone. Sustainable for hours. Most training volume should be here.
- Zone 3 (Moderate, 70–80%): Tempo pace. Slightly uncomfortable but sustainable for 20–60 minutes. Improves lactate threshold.
- Zone 4 (Hard, 80–90%): Threshold training. Produces lactate buildup. Typically 5–20 minute efforts. Improves max aerobic power.
- Zone 5 (Maximum, 90–100%): VO₂max intervals. All-out sprints and short, intense efforts. Maximum heart rate achieved here. Brief efforts only.
Worked example
A 30-year-old runner with a resting heart rate of 60 bpm, using the classic formula (220 − age):
MHR = 220 − 30 = 190 bpm
Heart-rate reserve = 190 − 60 = 130 bpm
Zone 2 (60–70% reserve) = 60 + 0.6 × 130 to 60 + 0.7 × 130 = 138–151 bpm
For comparison, using the Tanaka formula (208 − 0.7 × age): MHR = 208 − 0.7 × 30 = 187 bpm. This is 3 bpm lower, shifting all zones slightly downward.
Frequently asked questions
Why is Zone 2 training so popular?
Zone 2 builds aerobic fitness without much fatigue cost. You can sustain it for hours, recover from it overnight, and stack up training volume with low injury risk, which is why elite endurance athletes put 70–80% of their training time there. A useful field check: at Zone 2 effort you can hold a conversation in full sentences.
How do I find my true maximum heart rate?
The reliable ways are a supervised stress test or an all-out field effort: a hard 5–10 minute hill climb on a bike, or repeated uphill running sprints at the end of a workout. Wear a chest-strap heart rate monitor and record the highest value you reach. Formulas are population averages, so once you have a measured max, use it in this calculator instead.
Are 220-age formulas accurate?
Only roughly. The 220 − age formula came from a small sample decades ago, and individual variation runs ±10–12 bpm. For a 30-year-old it predicts 190 bpm, but a true max anywhere from 178 to 202 bpm is normal depending on genetics and sport background. Tanaka (208 − 0.7 × age) fits adults better on average, and a measured max beats both. Comparing your zones to someone else's tells you little, since max heart rate says nothing about fitness.
This calculator is for informational and educational purposes only and is not medical advice. Its results are general estimates, not an individual assessment. Talk to a doctor, registered dietitian, or other qualified health professional before making decisions about your health, diet, or exercise.