How the zones are calculated
Max heart rate is estimated from age, then each zone is a percentage of either max HR or heart-rate reserve.
Karvonen: (max HR − resting HR) × % + resting HR
- Tanaka: 208 − 0.7 × age, the usual choice for adults.
- Fox: 220 − age, the classic rule of thumb; it tends to overestimate in older adults.
- Without a resting HR the zones use plain percentages of max HR.
Training zones
| Zone | % of max | What it feels like |
|---|---|---|
| 1 · Very light | 50–60% | Easy; warm-up and recovery |
| 2 · Light | 60–70% | Conversational; base endurance |
| 3 · Moderate | 70–80% | Steady effort; aerobic fitness |
| 4 · Hard | 80–90% | Short sentences; speed and power |
| 5 · Maximum | 90–100% | Very hard; intervals only |
Most easy running sits in zone 2, while intervals reach zones 4–5. A common week is about 80% easy and 20% hard.
Tips
- Measure resting HR right after waking, before coffee, on three days and use the average.
- A watch's max HR is often calculated with the same formula, not measured.
- Heat, caffeine, stress and altitude raise heart rate for the same effort.
Standards and sources
- Tanaka H, Monahan KD, Seals DR. Age-predicted maximal heart rate revisited. Journal of the American College of Cardiology, 2001
- American College of Sports Medicine (ACSM) · exercise intensity guidelines
Last reviewed October 27, 2026
Frequently asked questions
Which max HR formula should I use?
Tanaka (208 − 0.7 × age) fits adults better than the old 220 − age rule. Both are estimates, and real max HR varies by about ±10–12 bpm between people.
What is the Karvonen method?
It builds zones from heart-rate reserve: (max HR − resting HR) × percentage + resting HR. It is more personal, but only as good as your resting HR reading.
What is zone 2?
60–70% of max HR, an easy pace where you can still hold a conversation. It is the usual base-building zone for endurance.
Is this medical advice?
No. Medication, illness, pregnancy and heart conditions change how heart rate responds. Ask a doctor before training to a target heart rate.