| Zone | Name | % Max HR | HR range (bpm) | Perceived effort | Purpose |
|---|
About heart rate zones
Heart rate zones let you structure training intensity around specific goals, aerobic base, lactate threshold, VO₂max. They are calculated as a percentage of your maximum heart rate (HRmax).
The 5 heart rate zones
| Zone | % HRmax | Name | Purpose |
|---|---|---|---|
| 1 | 50-60% | Recovery | Active recovery, warm-up and cool-down |
| 2 | 60-70% | Fat burning / Endurance | Long slow distance, aerobic base building |
| 3 | 70-80% | Aerobic | Tempo runs, sustained moderate effort |
| 4 | 80-90% | Threshold | Lactate threshold training, race pace |
| 5 | 90-100% | VO₂max / Anaerobic | Intervals, maximum effort sprints |
HRmax estimation formulas
- 220 − age: the classic formula. Quick estimate but has a high standard deviation (±10-12 bpm)
- Tanaka formula: 208 − 0.7 × age. More accurate for adults, especially over 40
- Measured HRmax: most accurate, measured during a supervised maximal effort test on a treadmill or field test
Karvonen formula (heart rate reserve)
The Karvonen method uses heart rate reserve (HRmax − resting HR) to calculate more personalized zones:
Target HR = resting HR + (HRmax − resting HR) × % intensity
Example: HRmax = 190, resting HR = 55, target zone 4 (80%): 55 + (190−55) × 0.80 = 55 + 108 = 163 bpm
Karvonen zones are typically 5-10 bpm higher than simple percentage zones for the same intensity, they account for individual cardiovascular fitness.
The 220-age formula: a convenient myth
The formula 220 - age was popularised in 1970 by Fox and Haskell but was never validated by a rigorous study. It was derived from a rough visual fit of just a handful of data points. A 2002 meta-analysis by Tanaka et al. (published in the Journal of the American College of Cardiology) analysed 351 studies covering 18,712 subjects and found that 208 - 0.7 x age was significantly more accurate, particularly for people over 40. Even so, individual variation remains large: at age 40, actual HRmax in healthy adults ranges from roughly 155 to 195 bpm regardless of formula. If precision matters, for cardiac rehab, competitive sport, or medical testing, use a supervised maximal effort test.
The "fat-burning zone" myth
Zone 2 (60-70% HRmax) is sometimes called the "fat-burning zone" because a higher proportion of calories at that intensity comes from fat rather than carbohydrate. This is technically true. However, the total calorie burn per minute at Zone 2 is much lower than at Zone 4. A 30-minute Zone 4 run burns more total fat in absolute terms than a 30-minute Zone 2 run, even though Zone 4 derives a smaller percentage from fat. The practical takeaway: Zone 2 is valuable for aerobic base building and recovery, not because it burns more fat, but because you can sustain it for long durations with minimal recovery cost.
NHS physical activity guidelines and heart rate
The NHS recommends adults accumulate at least 150 minutes of moderate-intensity aerobic activity per week, or 75 minutes of vigorous-intensity. Moderate intensity corresponds to roughly Zone 2-3 (60-80% HRmax), where breathing quickens but conversation is still possible. Vigorous intensity corresponds to Zone 4-5 (80-90%+), where sustained conversation becomes difficult. Any combination of moderate and vigorous counts towards the 150-minute guideline, with vigorous minutes counting double.