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 - ageEach zone is then a fixed percentage band of that maximum, following the standard five-zone model:
Zone 1 50–60% Recovery / warm-up
Zone 2 60–70% Aerobic / easy base building
Zone 3 70–80% Tempo / moderate aerobic
Zone 4 80–90% Threshold / hard sustained effort
Zone 5 90–100% VO2max / anaerobic sprintMultiplying each percentage by your max HR gives the bpm range you should hold for that zone.
What each zone is for
Zone 1 is active recovery — light movement that increases circulation without adding fatigue. Most cool-down and recovery-day running sits here.
Zone 2 is where most of your weekly mileage should live. It builds the aerobic base, improves mitochondrial density, and trains the body to burn fat efficiently. Long runs, easy runs, and recovery miles belong here. The common error is running Zone 2 miles too hard and drifting into Zone 3 — which adds fatigue without proportionally more aerobic benefit.
Zone 3 is the “comfortably hard” zone — sustained effort you can hold for 30–60 minutes. It builds aerobic capacity but is metabolically costly, so overuse of Zone 3 is tiring without the specific gains of Zones 4–5. Some coaches call this the “junk miles” zone when used excessively.
Zone 4 is threshold training — the intensity around your lactate threshold, roughly the pace you could hold in a hard hour-long race. Tempo runs, cruise intervals, and threshold repeats live here.
Zone 5 is short and hard — intervals, strides, and efforts close to maximum. Recovery between Zone 5 efforts is long because the intensity is extreme. Most runners spend very little weekly time here; a few percent of total volume is typically enough.
Notes on estimating max HR
Age formulas carry a standard error of around plus or minus ten beats per minute. A 40-year-old’s true max could reasonably be anywhere from 170 to 190 bpm. That range shifts every zone by the same amount, so zones calculated from an inaccurate max are consistently off in one direction. If your training depends on precision — for a race build or injury rehabilitation — do a supervised field test and enter the measured value directly.