Heart Rate Zone Calculator (Fat Burn & Cardio, 2026)
Use our free Heart Rate Zone Calculator to work out your five training zones from your age and resting heart rate. It estimates your max HR as 220 minus age, then uses the Karvonen formula to give heart rate ranges for each zone: recovery, fat burn, aerobic, anaerobic, and VO2 max. No signup, no upload.
How Heart Rate Zones Work
The Karvonen formula sets your target heart rate as (max HR - resting HR) × intensity + resting HR. Because it factors in your resting heart rate, it personalises each zone better than a simple percentage of max HR alone. Zone 2 (60-70% of reserve) is the fat-burn zone where a higher share of energy comes from fat. Zone 4-5 is where you build speed and VO2 max.
How to Use Our Heart Rate Zone Calculator
- Open the Heart Rate Zone Calculator tool.
- Enter your age.
- Enter your resting heart rate (bpm).
- Read your max heart rate.
- Use the zone ranges to guide training.
Heart Rate Zone Reference (30 years, 65 bpm resting)
| Zone | Intensity | HR Range | Training Benefit |
|---|---|---|---|
| 1 — Recovery | 50-60% | 130-142 | Active recovery |
| 2 — Fat burn | 60-70% | 142-155 | Aerobic base, fat utilization |
| 3 — Aerobic | 70-80% | 155-168 | Cardio endurance |
| 4 — Anaerobic | 80-90% | 168-181 | Lactate threshold |
| 5 — VO2 max | 90-100% | 181-190 | Maximum performance |
Common Use Cases for a Heart Rate Zone Calculator
- Training program design — set heart rate targets for each workout type.
- Fat-burn optimization — stay in zone 2 for maximum fat utilization.
- Endurance training — build aerobic base with zone 2-3 workouts.
- HIIT planning — structure intervals that spike into zones 4-5.
- Recovery management — ensure easy days stay in zone 1 for active recovery.
FAQ
What is the Karvonen formula?
Target HR = (max HR - resting HR) × intensity + resting HR. It personalises zones by factoring in your resting heart rate.
How is maximum heart rate estimated?
The common estimate is 220 minus your age. It is a rough average — your true max can vary by 10-15 bpm.
Which zone burns the most fat?
Zone 2 (60-70% of reserve) is the fat-burn zone. A higher share of energy comes from fat here, making it ideal for aerobic base building.
How do I find my resting heart rate?
Measure it first thing in the morning before getting out of bed. Most adults sit between 60 and 100 bpm.
Is this heart rate zone calculator free?
Yes, completely free with no signup. All math runs in your browser — nothing is uploaded.
Try our free Heart Rate Zone Calculator to find your personalized training zones.