Health Guide
How Heart Rate Zones Work
The five training zones, what each is for, and how they're calculated from your estimated maximum heart rate.
Last updated: August 29, 2026
Heart rate zones divide your training intensity into bands, each associated with a different kind of adaptation. They turn "go hard" and "go easy" into something you can actually measure while you exercise.
The zones are percentages of your maximum
Everything starts with your maximum heart rate — the highest rate your heart can reach during all-out effort. Zones are then defined as percentages of that figure:
| Zone | % of HRmax | Effort |
|---|---|---|
| Zone 1 | 50–60% | Very light |
| Zone 2 | 60–70% | Light |
| Zone 3 | 70–80% | Moderate |
| Zone 4 | 80–90% | Hard |
| Zone 5 | 90–100% | Maximum |
This is the common five-zone model used in endurance training. Our Heart Rate Zones Calculator computes all five from your age.
A worked example
We estimate maximum heart rate with the Tanaka formula, from a 2001 study in the Journal of the American College of Cardiology:
HRmax = 208 − (0.7 × age)For a 30-year-old:
208 − (0.7 × 30) = 187 bpmApplying the zone percentages to 187 bpm:
| Zone | Range |
|---|---|
| Zone 1 | 94–112 bpm |
| Zone 2 | 112–131 bpm |
| Zone 3 | 131–150 bpm |
| Zone 4 | 150–168 bpm |
| Zone 5 | 168–187 bpm |
You may have seen the older 220 − age rule, which gives 190 bpm for the same person. Why we use 208 − 0.7 × age explains why we don't.
What each zone is for
- Zone 1 — recovery and warm-up. Genuinely easy; you can hold a full conversation.
- Zone 2 — the aerobic base. Sustainable for long periods, and where a large share of endurance training volume typically sits.
- Zone 3 — moderate, sometimes called tempo. Harder to sustain, conversation becomes difficult.
- Zone 4 — hard efforts, usually done as intervals. Breathing is laboured.
- Zone 5 — maximum effort, sustainable only in short bursts.
A common pattern in recreational training is spending most sessions in Zone 3 — too hard to build a genuine aerobic base, too easy to be a real hard session. Deliberately separating easy from hard is usually more productive than living in the middle.
How much to trust the numbers
The Tanaka formula is a population estimate. Individual maximum heart rate varies by roughly ±10 bpm from what any age-based formula predicts, and some people sit further out than that.
For a 30-year-old, a ±10 bpm uncertainty in HRmax shifts every zone boundary by several beats. That is why we label this calculator moderate confidence and why the zones are best treated as approximate bands — see how accurate are heart rate zones.
The bottom line
Zones are percentages of your maximum heart rate, estimated from your age. Zone 2 builds aerobic base, Zone 4 and 5 build top-end fitness, and the middle is easy to over-use. Get your own zones from the Heart Rate Zones Calculator, and treat every boundary as approximate.
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