Target Heart Rate Calculator
Training by heart rate
Exercise intensity correlates roughly with heart rate as a percentage of your maximum. Working in different zones produces different adaptations — low zones build aerobic base, middle zones build threshold, high zones build VO2max. Most endurance improvement comes from Zone 2 volume, not beating yourself up at high intensity.
The classic '220 − age' formula is a decent starting estimate but can be off by 10–15 bpm for individuals. Lab testing or a calibrated field test (Karvonen method with known resting and maximum HR) gets you personalized zones. This calculator shows standard zone splits from your estimated max.
Frequently asked questions
What are heart rate zones used for?
Different training effects at different intensities. Zone 1 (50–60% max HR) is recovery. Zone 2 (60–70%) builds aerobic base — the endurance zone. Zone 3 (70–80%) is tempo. Zone 4 (80–90%) is threshold. Zone 5 (90–100%) is VO2max / sprint work. Most endurance gains come from Zone 2 volume, not beating yourself up in Zone 4+.
How accurate is the 220-minus-age formula?
Reasonable as a starting estimate, but can be off by ±15 bpm for individuals. The Tanaka formula (208 − 0.7×age) is slightly more accurate in older populations. For real precision, do a lab VO2max test or a well-calibrated field test (e.g., Karvonen method with known rest + max HR).
Should I train by heart rate or perceived effort?
Both have a place. Heart rate is objective and great for Zone 2 work (where it's hard to tell effort from feel). Perceived effort (RPE 1–10) auto-adjusts for bad sleep, heat, stress. Elite athletes use both: heart rate for baseline training, RPE for race-day pacing.
Why does my heart rate spike on easy runs?
Cardiac drift: HR creeps up 5–10 bpm during extended effort as body temperature rises, even at steady pace. Dehydration, heat, lack of sleep, caffeine, and lack of base fitness all amplify it. It's not usually cause for concern — it normalizes with training.
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