Cardiorespiratory Fitness
Heart Rate Zones Calculator
Your five heart-rate training zones are percentages of your maximum heart rate (estimated as 208 minus 0.7 times your age). Zone 2, roughly 60 to 70 percent of max, is the aerobic base most people skip; zones 4 and 5 build top-end capacity. Adding your resting heart rate switches to the more personalised Karvonen method.
Your five training zones in beats per minute, from your age. Add a resting heart rate and the maths switches to the more individual Karvonen method. The zone that matters most for most runners is the one they skip: Zone 2.
Why zones beat guessing
Most recreational runners train in a grey middle: their easy runs are a bit too hard and their hard runs are a bit too easy, so nothing gets properly trained. Heart rate zones fix that by putting a number on effort. The single biggest change for most people is running the majority of their weekly volume slower, in Zone 2, so the hard sessions can be genuinely hard. In Singapore's heat and humidity, a given pace costs more beats than it would in cool weather, which is exactly why training to heart rate keeps your easy days honestly easy. It sits alongside your VO2 max as one half of the cardiorespiratory picture.
The maths behind the zones
Max heart rate: Tanaka H et al. 2001, J Am Coll Cardiol (HRmax = 208 minus 0.7 times age). Heart-rate-reserve method: Karvonen MJ et al. 1957.
| Zone | Intensity | What it trains |
|---|---|---|
| Zone 1 | 50–60% | Recovery, warm-up, cool-down |
| Zone 2 | 60–70% | Aerobic base (most of your volume) |
| Zone 3 | 70–80% | Tempo, steady sustained effort |
| Zone 4 | 80–90% | Threshold intervals |
| Zone 5 | 90–100% | Maximal, short VO2-max intervals |
Heart rate zones, common questions
- How are my heart rate zones calculated?
- First we estimate your maximum heart rate with the Tanaka formula, 208 minus 0.7 times your age, which fits the population better than the old 220-minus-age rule. If you add a resting heart rate, the zones use the Karvonen heart-rate-reserve method, which anchors on both your resting and max rates for a more individual result. Without it, each zone is a straight percentage of your max.
- What is Zone 2 and why does it matter?
- Zone 2 is easy, conversational effort, roughly 60 to 70 percent. It is the aerobic base zone, and it is the one most runners skip because it feels too slow. Building volume here improves the body's ability to use fat and oxygen, raises your aerobic ceiling over time, and leaves you fresh enough to train often. Most of your weekly training should sit in Zone 2.
- How accurate is an age-based max heart rate?
- It is an estimate. Any age formula carries a spread of plus or minus roughly 10 to 12 beats per minute, because true max heart rate is largely genetic and does not track fitness. If you want precision, a graded test or a reliable chest-strap reading during a hard effort beats any formula. The zones here are a sound starting frame, not a fixed law.
- Should I train by heart rate or by pace?
- Both have a place. Heart rate reflects internal effort and is honest in Singapore's heat and humidity, where a given pace costs more beats than it would in cool weather. Pace is cleaner for shorter, faster sessions where heart rate lags the effort. Many runners pace their easy runs by heart rate and their hard intervals by pace or feel.
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