Heart rate zones for running: how to calculate and use them
Calculate your 5 running heart rate zones with the Karvonen formula. Explore the zone chart, a worked example and how to use each zone in training.
Key takeaways
- The 220 − age formula can be off by 10 bpm or more.
- Use your real max and resting heart rate with the Karvonen method.
- Zone 2 = 60–70% of your reserve: where most of your runs belong.
- Spend around 80% of your running time at low intensity.
Article contents
Training by heart rate zones is the simplest way to give every session the intensity it needs: keeping easy runs truly easy and making hard days count. But zones only work if they are calculated properly, and the formula almost everyone uses has a huge margin of error. Here is how to calculate them well and how to use them.
What are heart rate zones?
They are ranges of beats per minute (bpm) that correspond to different effort levels and, broadly, to different training adaptations. The most common model has five zones, from Z1 (very easy) to Z5 (maximal). To calculate them you need two numbers: your maximum heart rate and your resting heart rate.
How to calculate your maximum heart rate
The 220 − age formula (and its problem)
It is the best known: subtract your age from 220. A 35-year-old would have a maximum of 185 bpm. The Tanaka formula (208 − 0.7 × age) is somewhat more accurate in adults and would give 183.5 bpm.
The problem is that both describe a population average. For any one person, the real maximum can sit 10 bpm or more above or below the formula. A 10 bpm error is enough to turn your “zone 2” into zone 3, or to leave your intervals short.
Better: measure it
The most reliable way, short of a lab test, is to look at the highest heart rate you have recorded in genuinely maximal efforts: the final sprint of a 5K or 10K race, or the top of a very hard hill. If you have trained with a heart rate monitor for months, your maximum is probably already in your history. Only do a dedicated test if you are healthy and fit, and after a thorough warm-up.
Your resting heart rate
Measure it on waking, still lying down, over several days, and take the average. If your watch tracks your sleep, it probably gives you this number already. As your aerobic fitness improves, your resting heart rate usually drops.
How to calculate your zones with the Karvonen method
The Karvonen method uses your heart rate reserve (maximum minus resting), so it accounts for your fitness, not just your age:
Target HR = (max HR − resting HR) × % intensity + resting HR
Example: with a maximum of 185 bpm and a resting rate of 55 bpm, the reserve is 130 bpm. 70% of the reserve would be 130 × 0.7 + 55 = 146 bpm.
| Zone | % of reserve | Heart rate (example) | How it feels |
|---|---|---|---|
| Z1 · Recovery | 50–60% | 120–133 bpm | Very easy; recovery jog or warm-up |
| Z2 · Aerobic | 60–70% | 133–146 bpm | Conversational; most of your runs |
| Z3 · Tempo | 70–80% | 146–159 bpm | Moderate; short sentences |
| Z4 · Threshold | 80–90% | 159–172 bpm | “Comfortably hard”; a few words |
| Z5 · VO₂ max | 90–100% | 172–185 bpm | Very hard; short intervals |
Some apps and watches use different percentages or base zones on threshold heart rate rather than maximum. That’s fine: what matters is sticking to one system and basing it on your real numbers.
Lactate threshold heart rate
Threshold is the intensity above which effort stops being sustainable for long: roughly what you could hold running all-out for an hour. Many coaches prefer to anchor zones to your threshold heart rate because it is more stable and more useful than your maximum.
A simple test: after warming up, run 30 minutes as hard as you can sustain evenly, on your own. Your average heart rate over the last 20 minutes is a good estimate of your threshold heart rate.
How to use zones in your training
Most well-trained distance runners spend around 80% of their time at low intensity (Z1–Z2) and the remaining 20% at moderate and high intensity. Most recreational runners have the opposite problem: they run almost everything in Z3 — too fast to recover, too slow to build speed.
- Easy and long runs: Z2. If your heart rate drifts into Z3 on a hill, slow down or walk.
- Threshold work: Z4, in blocks of 8 to 20 minutes.
- Short intervals: Z5. Heart rate lags here, so for reps under 2 minutes go by pace or feel instead.
Why your heart rate changes from day to day
The same pace doesn’t always produce the same heart rate. Heat and humidity, dehydration, caffeine, stress, poor sleep and accumulated fatigue all push it up. And in long efforts, heart rate creeps up even at a steady pace (so-called cardiac drift).
That is why it is worth looking at how you wake up too. Overnight heart rate variability (HRV), compared with your usual values, is one of the best clues as to whether today is a day to push or to back off.
Zones go hand in hand with pace: to translate effort into minutes per kilometre, read our running pace guide. And if you are training for a race, see how they apply in our half marathon plan.
Frequently asked questions
What is zone 2 in running?
An easy, sustainable intensity: 60 to 70% of your heart rate reserve with the Karvonen method. You can talk in full sentences. It is where most of your runs should be.
Is 220 minus age accurate?
It is a starting point, but for any one person it can be off by 10 bpm or more. It is better to use the maximum you have recorded in real efforts or a field test.
Why is my heart rate so high even when I run slowly?
It is common when you start training by zones: heat, dehydration, fatigue or a wrist sensor confusing heart rate with cadence can all raise the reading. After weeks of easy running, your pace at the same heart rate usually improves.
How often should I recalculate my zones?
Your maximum changes little, but your resting heart rate and threshold improve with training. Review your zones every 6 to 8 weeks or after a race or test.
We write practical training guides with the same logic the app uses: measure first, assume nothing.
This content is for information only and does not replace advice from a doctor or coach. If you have an injury or a heart condition, or have not exercised in a while, check with a professional before starting a plan.
