How are the five zones defined?

Each zone is a percentage band of your maximum heart rate: Zone 1 is 50-60%, Zone 2 is 60-70%, Zone 3 is 70-80%, Zone 4 is 80-90%, and Zone 5 is 90-100%. This is the five-zone model used by Garmin and ACSM.

Which max HR formula is more accurate?

The Tanaka formula (208 minus 0.7 times age) tracks measured maximum heart rate across a wide age range better than the classic 220-minus-age, which tends to overestimate for younger people and underestimate for older ones.

Should I estimate or measure my max HR?

Age formulas carry a standard error of around plus or minus ten beats per minute. A field test or a lab measurement gives far more personalised zones, so measure directly if your training depends on precise targets.

What is Zone 2 used for?

Zone 2 is the easy aerobic zone where most endurance base mileage should sit. Training there builds mitochondrial density and fat-burning capacity while keeping fatigue low enough to run frequently.

Why are my zones from heart rate different to pace zones?

Heart rate lags effort and drifts upward with heat, fatigue, and dehydration, so a steady pace can show different heart rates on different days. Use both, but trust heart rate less on short, hard intervals.

Running Heart Rate Zone Calculator

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Train at the right intensity, every run

Running by feel works, but heart rate zones give you an objective target so easy runs stay genuinely easy and hard sessions hit the intended stress. This calculator turns a single number — your maximum heart rate — into five training zones in beats per minute, each tied to a clear purpose, from recovery jogging up to VO2max intervals.

How it works

If you do not have a measured maximum, the tool estimates it from your age. The default is the Tanaka equation, which is more accurate across ages than the older rule:

Tanaka:   HRmax = 208 - 0.7 * age
Classic:  HRmax = 220 - age

Each zone is then a fixed percentage band of that maximum, following the standard five-zone model:

Zone 1  50-60%   Recovery
Zone 2  60-70%   Aerobic / easy
Zone 3  70-80%   Tempo
Zone 4  80-90%   Threshold
Zone 5  90-100%  VO2max / anaerobic

Multiplying each percentage by your max HR gives the bpm range you should hold for that zone.

Tips and notes

Most of your weekly mileage should sit in Zones 1 and 2 — the common mistake is running easy days too hard, which leaves you too tired to push on the sessions that matter. Remember that age formulas have a wide margin: a 40-year-old’s true max could be anywhere from roughly 170 to 190 bpm. If your training hinges on precise targets, do a supervised field test or lab assessment and enter that measured maximum directly for zones tailored to you rather than to a population average.