Health · 4 min read
Heart Rate Zones Explained: What Zones 1–5 Actually Do
Heart rate zones are just bands of effort, measured in beats per minute, that tell you how hard your body is working. Most systems use five. Zone 1 is barely-trying easy, zone 5 is flat out, and each one in between trains something slightly different. The point of using them is simple: they stop you running every session at the same medium-hard effort, which is what most people do by default.
How the zones are calculated
You need one number first: your maximum heart rate. The old formula is 220 minus your age. A better estimate for most people is 208 − 0.7 × age (the Tanaka formula). Either way, it's an estimate, and real maximums vary by 10 beats or more either side. We dig into that in is 220 minus age accurate?
The zones are then percentages of that maximum:
| Zone | % of max HR | How it feels |
|---|---|---|
| 1 — Recovery | 50–60% | Very easy, could do it all day |
| 2 — Endurance | 60–70% | Easy, full conversation possible |
| 3 — Tempo | 70–80% | Moderate, short sentences |
| 4 — Threshold | 80–90% | Hard, a few words at a time |
| 5 — Maximum | 90–100% | All-out, no talking |
The heart rate zone calculator works these out for you, and can use your resting heart rate too (the Karvonen method), which fits fitter people better.
Example: a 40-year-old
Using Tanaka, max heart rate is 208 − 28 = 180 bpm. The zones come out as:
- Zone 1: 90–108 bpm
- Zone 2: 108–126 bpm
- Zone 3: 126–144 bpm
- Zone 4: 144–162 bpm
- Zone 5: 162–180 bpm
What each zone is actually for
Zone 1 is for recovery. Warm-ups, cool-downs, gentle days after a hard session. It helps blood flow without adding much fatigue.
Zone 2 is where endurance is built. Your body gets better at delivering oxygen to muscles and at using fat for fuel. It feels almost too easy, which is exactly why people skip it. For most endurance athletes it makes up the bulk of their training. More on that in zone 2 heart rate: how to find it.
Zone 3 is the "comfortably hard" middle ground. Useful in small doses, like steady tempo runs, but it's also where many people accidentally spend all their time. It's hard enough to make you tired, but not hard enough to push your top end.
Zone 4 is threshold work: intervals of a few minutes that raise the pace you can hold before fatigue builds quickly. This is where race-specific fitness improves.
Zone 5 is short, maximal efforts, usually under a minute or two. Powerful stuff, but very tiring. Once a week at most for most people, and often less.
How much time in each zone?
Studies of elite endurance athletes tend to find a "polarised" pattern: around 80% of training at low intensity (zones 1–2) and around 20% at high intensity (zones 4–5), with relatively little in the middle. You don't need to be that precise. A simple version for a normal person training three to five times a week:
- Most sessions easy (zone 2, conversational)
- One session a week with some hard efforts (zone 4)
- Very little deliberate zone 3 grinding
Why your watch and your zones sometimes disagree
- Wrist sensors lag. During short intervals, your heart rate may not show up until the interval is nearly over. Chest straps are more accurate.
- Heart rate drifts. On a long or hot session, heart rate creeps up even at the same pace. That's normal.
- Caffeine, poor sleep and stress all nudge heart rate up. On those days, go by feel.
Keep it simple
If you don't own a heart rate monitor, the talk test gets you most of the way. Full sentences is zone 2. Short sentences is zone 3. A few words is zone 4. Can't talk is zone 5. Zones are a tool to make your easy days easy and your hard days hard, and that's the whole trick.
Frequently asked questions
What are the five heart rate zones?
Zone 1 (50–60% of max HR) for recovery, zone 2 (60–70%) for endurance, zone 3 (70–80%) for tempo, zone 4 (80–90%) for threshold work and zone 5 (90–100%) for maximal efforts.
What heart rate zone should I train in most?
For most people building fitness, zone 2 (easy, conversational) should be the majority of training time, with a smaller amount of harder zone 4 work.
How do I find my heart rate zones?
Estimate your max heart rate (for example 208 − 0.7 × age) and take percentages of it, or use the Karvonen method with your resting heart rate for a more personal result.
Do I need a heart rate monitor to train by zones?
No. The talk test is a good substitute: full sentences means easy, a few words at a time means hard.