🧮 Heart Rate Zone Calculator
Training by heart rate zones optimizes workouts: you will know when you are burning fat and when you are improving endurance.
📊 Heart Rate Zone Statistics and Facts
5-Zone System
Zone 1 (50–60% MHR): recovery. 2 (60–70%): fat burning. 3 (70–80%): aerobic. 4 (80–90%): anaerobic. 5 (90–100%): maximum.
Fat-Burning Myth
In zone 2 the highest percentage of fat is burned, but the fewest calories per minute. In more intense zones, more calories are burned in total.
Training Distribution
80/20 rule: 80% of time in low zones (1–2), 20% in high zones (4–5). This is the optimal balance for progress and recovery.
💡 Practical Tips
- 80/20 rule — professional endurance athletes spend ~80% of training time in zones 1–2 and only 20% in high zones. This helps avoid overtraining.
- Use a Chest Strap — wrist monitors have a 5–15% error. A chest strap is ECG-accurate and essential for serious heart rate training.
- Periodize — for beginners: 6 weeks in zones 1–2, then after 2–3 weeks move to higher zones. For experienced athletes: a weekly cycle.
What Are Heart Rate Zones
Heart rate zones are intensity intervals based on heart rate. They allow you to describe with a single number “how hard” you are working and to determine what effect a workout provides. Most often, zones are calculated as percentages of maximum heart rate.
📊 Zones and What They Provide
| Zone | % of max heart rate | What it trains | How it feels |
|---|---|---|---|
| 1 — Recovery | 50–60 % | Recovery, circulation | Easy, can talk |
| 2 — Base | 60–70 % | Aerobic base, fat utilization | Can talk in sentences |
| 3 — Tempo | 70–80 % | Overall capacity, heart work | Can speak in short phrases |
| 4 — Threshold | 80–90 % | Speed/endurance threshold | Hard, talking impossible |
| 5 — Maximum | 90–100 % | Sprint capacity | Maximum load, maintained briefly |
🧮 How to Determine Your Zones
- Determine your maximum heart rate (see maximum heart rate calculator) — but remember that formulas are approximate.
- Calculate zone boundaries as percentages of maximum heart rate (table above).
- If you have actual threshold tests (e.g., with a stress test), use them — it is more accurate.
- Limitation: use a chest strap, not a wrist sensor, if you want accuracy.
💡 How to Train in Practice
- Most of the time in zones 1–2 — the base grows there, not in high zones.
- Zone 3 — tempo workouts, 20–40 min.
- Zone 4 — intervals (e.g. 5×4 min with breaks).
- Zone 5 — only in short bursts, and not every week.
- Don't chase heart rate alone: fatigue, heat, caffeine and stress raise heart rate — the same pace may "seem" harder, even though the load has not actually changed.
⚠️ Where the Numbers Go Wrong
- Wrist Sensors often read incorrectly during intense exercise.
- Maximum Heart Rate Formulas have an error of ±10–15 beats/min.
- Heart Rate "Drift" — during a long workout at the same pace, heart rate rises on its own.
- Caffeine, Illness, Sleep change heart rate independently of the load.
- Zones Are a Guide, Not a Law — how you feel ("I can talk / I can't talk") is often more reliable.