"Run easy, Zone 2" sounds like a clear instruction. But depending on how the zones were worked out, Zone 2 for the same runner can be 111–130 bpm or 143–151 bpm. That's the difference between a jog and a steady run.
This guide explains the three common ways to calculate heart rate zones, shows the same runner under each, and gives coaches a simple way to choose.
The five zones
Most running watches and coaching apps use five zones:
| Zone | Name | What it feels like |
|---|---|---|
| Zone 1 | Recovery | Very easy; full conversation |
| Zone 2 | Easy | Easy; you can talk in sentences |
| Zone 3 | Steady | Comfortably hard; short sentences |
| Zone 4 | Threshold | Hard; a few words at a time |
| Zone 5 | Max | Very hard; can't talk |
The names are the same everywhere. What changes is how the heart-rate edges of each zone are worked out.
Method 1: % of max heart rate
Each zone is a share of max heart rate:
- Zone 1: 50–60%
- Zone 2: 60–70%
- Zone 3: 70–80%
- Zone 4: 80–90%
- Zone 5: 90–100%
Good: it needs one number, and it's what most watches use out of the box.
Not so good: it ignores fitness. Two runners with a max of 185 get identical zones, even if one has a resting heart rate of 45 and the other 70.
Finding max heart rate: the formula 208 − 0.7 × age (Tanaka) is a reasonable start, but people vary by 10 beats or more either way. The highest heart rate seen at the end of a hard race or hill repeats is usually closer.
Method 2: heart-rate reserve (Karvonen)
Heart-rate reserve is max minus resting heart rate. Each zone is resting heart rate plus a percentage of the reserve, using the same percentages as above:
Zone heart rate = resting + % × (max − resting)
Good: it accounts for fitness. A lower resting heart rate moves the zones up, which matches how fitter runners feel at a given effort.
Not so good: it needs an accurate resting heart rate. Measure it on waking, before getting out of bed, on a few mornings.
Method 3: threshold heart rate
Threshold heart rate is roughly the highest heart rate you can hold for about an hour. Zones are shares of it:
- Zone 1: below 85%
- Zone 2: 85–90%
- Zone 3: 90–95%
- Zone 4: 95–100%
- Zone 5: above 100%
Good: it's tied to a real effort rather than a formula, so it's the most accurate for trained runners.
Not so good: it needs a test. Run 30 minutes as hard as you can hold on your own and take your average heart rate for the last 20 minutes, or use the average from a recent 10K race. Repeat every couple of months as fitness changes.
One runner, three answers
Take a runner with max heart rate 185, resting 55 and threshold 168:
| Zone | % of max | Heart-rate reserve | Threshold |
|---|---|---|---|
| Zone 1 | 93–111 | 120–133 | 55–143 |
| Zone 2 | 111–130 | 133–146 | 143–151 |
| Zone 3 | 130–148 | 146–159 | 151–160 |
| Zone 4 | 148–167 | 159–172 | 160–168 |
| Zone 5 | 167–185 | 172–185 | 168–185 |
For this runner, "% of max" Zone 2 is very gentle, while threshold-based Zone 2 is a solid aerobic run. Neither is wrong, but the athlete needs to know which one their coach means.
You can try your own numbers in our heart rate zone calculator.
Which method should coaches use?
- New or casual runners: % of max heart rate. It's simple, and it errs on the easy side.
- Most club runners: heart-rate reserve, once they've measured resting heart rate.
- Trained runners and anyone with a recent test or race: threshold heart rate.
Whichever you choose, use one method per athlete and keep it. Switching methods mid-block makes weeks impossible to compare.
The watch problem
Here's a trap many coaches fall into: you plan "Zone 2" and the athlete's watch uses its own zone settings, which may be a different method or a different max heart rate. The plan says one thing and the watch beeps at another.
Athelista avoids this by sending each zone to the watch as the athlete's own heart-rate range. "Zone 2" leaves Athelista as, say, 133–146 bpm, so the watch, the plan and the athlete all agree.
Easy should stay easy
Many coaches aim for about 80% of weekly running time in Zones 1–2. If an athlete's easy runs keep drifting into Zone 3, either the zones are set too low or the easy runs are too fast. Both are worth a conversation.