Target heart rate zones (Zones 1–5) in plain English

“Heart rate zones” are simply ranges of beats per minute (BPM) that represent how hard your body is working. The same workout can feel easy for one person and intense for another, so zones give you a personal intensity dial. When you train in specific zones, you bias your workouts toward different adaptations: recovery, fat oxidation, aerobic endurance, lactate threshold, or pure speed.

This calculator gives you two popular ways to estimate zones: (1) Percentage of max heart rate (fastest and most common), and (2) Karvonen (Heart Rate Reserve) (often feels “more personalized” because it uses your resting heart rate). Neither method is a medical diagnosis — they’re practical training estimates you can apply today.

Formulas used (and when to trust each one)

The classic estimate is: HR_max ≈ 220 − age. It’s popular because it’s easy. It can be off by quite a bit for individuals (some people naturally have a higher or lower max), but it’s still useful as a starting point, especially if you’re not sure what your max is.

Another commonly used estimate is: HR_max ≈ 208 − 0.7 × age. Some people prefer this because it often fits adults slightly better than 220−age, especially as age increases. This calculator shows both so you can compare.

Once we estimate HR_max, each zone is calculated as a percentage:

• Zone 1: 50–60% of HR_max (very easy / recovery)
• Zone 2: 60–70% of HR_max (easy aerobic / “fat burn”)
• Zone 3: 70–80% of HR_max (moderate endurance)
• Zone 4: 80–90% of HR_max (hard / threshold work)
• Zone 5: 90–100% of HR_max (very hard / VO₂ / sprints)

Karvonen uses your resting heart rate (RHR), which can make the zones feel more realistic if your RHR is unusually low or high. First calculate Heart Rate Reserve: HRR = HR_max − RHR. Then the target heart rate for a given intensity is: Target HR = RHR + (HRR × intensity). Example: If HR_max=190 and RHR=60, then HRR=130. At 70% intensity, Target=60 + 130×0.70 = 151 BPM.

If you don’t know your resting heart rate, use the %Max method. If you do know it (from a watch or morning measurement), Karvonen is worth using.

What each zone is best for

Zone 1 should feel easy. You can breathe through your nose and hold a full conversation. Use it for warm-ups, cooldowns, recovery days, and rebuilding consistency if you’re coming back after time off.

Zone 2 is the internet’s favorite zone for a reason: it’s sustainable, improves aerobic capacity, and helps build an endurance base. “Fat burn” doesn’t mean you only burn fat here — it means a higher proportion of energy comes from fat oxidation at these intensities. Practically, Zone 2 is great because you can do a lot of it without wrecking your recovery.

Zone 3 is the “comfortably hard” zone. Many people accidentally live here because it feels like you’re working, but it’s not quite intense enough to develop top-end speed efficiently. Still, it can be useful for tempo runs, moderate cycling, and improving durability.

Zone 4 is hard. It improves your ability to sustain faster efforts by raising your lactate threshold. Think structured intervals: 4×4 minutes, 3×8 minutes, or 20-minute tempo efforts (depending on fitness level).

Zone 5 is sprint territory. It’s very taxing and best used in short bursts with full recovery. You don’t need much Zone 5 to get benefits — quality matters more than volume.

Make your numbers feel “right” (even if the formula isn’t perfect)

Heart rate formulas are estimates. Here’s how to make zones practical:

• Use the talk test: Zone 2 should allow short sentences without gasping.
• Watch the lag: Heart rate can lag behind effort by 30–90 seconds, especially in intervals.
• Consider heat, caffeine, stress: they can raise heart rate at the same pace/power.
• Use resting HR trends: if your resting HR is up 5–10 BPM, you may be under-recovered.
• Medications matter: beta blockers can lower heart rate response — ask a clinician for guidance.

If you have chest pain, dizziness, fainting, or a heart condition, seek medical guidance before using intensity targets.

Examples you can copy-paste into your routine

Using 220−age: HR_max=190. Zone 2 (60–70%) is 114–133 BPM (simple method). With Karvonen: HRR = 190−60=130. Zone 2 becomes: 60 + 130×0.60 = 138 BPM (low end) to 60 + 130×0.70 = 151 BPM (high end). That’s a meaningful difference — and why Karvonen often feels more personal.

Do this 3–5 days/week: 30–45 minutes in Zone 2, plus 1 day of short intervals (Zone 4). This keeps fatigue manageable while building consistency.

Do this 4–6 days/week: 2–4 sessions in Zone 1–2, 1 threshold session (Zone 4), and optionally 1 short sprint session (Zone 5). This is close to the structure used in many endurance programs: a lot of easy work + a little hard work.

Pick a plan (beginner → advanced)

Beginner (3 days/week):

• Day 1: 25 min Zone 2
• Day 2: 20 min Zone 1–2 (easy) + mobility
• Day 3: 6×30 sec Zone 4 with 90 sec easy between

Intermediate (4–5 days/week):

• 2–3 days: 35–50 min Zone 2
• 1 day: 3×6 min Zone 4 with 3 min easy between
• 1 optional day: long easy Zone 2 (60+ min)

Advanced (5–6 days/week):

• 3–4 days: Zone 2 volume
• 1 day: threshold (Zone 4)
• 1 day: short sprints (Zone 5) or hill repeats

Frequently asked questions

• Which zone burns the most fat?

  At lower intensities (often Zone 2), a larger percentage of energy can come from fat oxidation. But total fat loss depends on overall energy balance across days and weeks. Zone 2 is popular because it’s sustainable and you can do a lot of it consistently.

• Why do my zones feel off compared to my watch?

  Watches often estimate zones using your past workouts, resting HR, and sometimes VO₂ max signals. This calculator uses standard formulas. If you have your resting HR, use Karvonen here for a closer match. Also remember hydration, stress, sleep, and heat can shift heart rate at the same pace.

• Do I need to know my true max heart rate?

  Not for general fitness. If you train competitively, a field test or lab test can refine your zones. For most people, starting with a formula + the talk test is enough to get great results.

• What if I’m on beta blockers?

  Some medications blunt the heart rate response. In that case, perceived exertion (RPE), breathing rate, and clinician guidance are better tools than generic zone formulas.

• Is Zone 3 “bad”?

  No — it’s just easy to overdo. Many people drift into Zone 3 every session, which can create fatigue without clear gains. Used intentionally (tempo workouts), Zone 3 can be valuable.

• How long should I stay in Zone 2?

  Beginners can start with 15–20 minutes and build up. Many people target 30–60 minutes per session. The “right” amount is the amount you can repeat consistently while recovering well.

• Can I use zones for walking?

  Yes — especially Zone 2. Inclines are helpful. If your heart rate won’t rise into Zone 2 on flat ground, increase pace slightly or add a gentle incline.

• What’s the most shareable result from this calculator?

  Your Zone 2 range. It’s the “sweet spot” people love talking about. Screenshot it, then try a 20‑minute Zone‑2 walk. Most people realize they were going too hard or too easy — instantly.