Heart Rate Zones Calculator
Your five training zones from age and resting heart rate, using the Karvonen (heart rate reserve) method.
- Estimated max heart rate (bpm)185
- Zone 1 starts — recovery (bpm)123
- Zone 2 starts — easy aerobic (bpm)135
- Zone 3 starts — tempo (bpm)148
- Zone 4 starts — threshold (bpm)160
- Zone 5 starts — maximal (bpm)173
Inputs used
- Age35 years
- Resting heart rate60 bpm
About this calculator
Training zones anchor effort to your physiology. This calculator uses the Karvonen method: estimate maximum heart rate as 220 minus age, subtract your resting rate to get your heart rate reserve, then place each zone at a percentage of that reserve added back onto resting.
The five zones follow the common convention: Zone 1 (50–60% of reserve) for recovery, Zone 2 (60–70%) for easy aerobic base — where most training time belongs, Zone 3 (70–80%) steady tempo, Zone 4 (80–90%) threshold, and Zone 5 (90–100%) maximal efforts.
The 220 − age rule is a population average with real individual spread (±10 beats is common), so treat these as starting brackets. A lab test or a hard hill session gives a truer personal maximum; your resting rate is best measured before getting out of bed.
Frequently asked questions
How are heart rate zones calculated?
Karvonen method: max HR ≈ 220 − age; reserve = max − resting; each zone starts at resting + (percentage × reserve). A 35-year-old with a resting rate of 60 has a reserve of 125, so Zone 2 starts at 60 + 0.6 × 125 = 135 bpm.
Which zone burns the most fat?
Zone 2 uses the highest proportion of fat for fuel, which is one reason easy aerobic volume dominates endurance training plans. Higher zones burn more total calories per minute but lean harder on carbohydrate.
Why use heart rate reserve instead of just max HR?
Percentages of raw max ignore fitness: two athletes with the same max but resting rates of 45 and 75 are in very different shape. Anchoring zones between resting and max personalises the brackets to your actual working range.
Results are informational only — not financial, medical or legal advice.