Metric Unit Calculator
The formula, your substituted values, and the evaluated result are shown below.
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View offerAffiliate link — we may earn a commission at no extra cost to you.Calculate heart rate reserve target using clearly labelled inputs.
This calculator uses the Karvonen (heart rate reserve) method. Your heart rate reserve is the difference between your maximum and resting heart rates, and the target adds a percentage of that reserve to your resting rate:
Target HR = resting HR + intensity % × (maximum HR − resting HR)
Because it includes your resting heart rate, it adjusts for fitness better than simple "% of max" methods.
Individuals can differ from these estimates by 10–20 bpm either way, so a measured maximum from a supervised test is best.
| Intensity | Zone | Feels like |
|---|---|---|
| 50–60% | Very light | Easy walking, warm-up |
| 60–70% | Light / aerobic base | Conversational pace |
| 70–80% | Moderate | Breathing harder, short sentences |
| 80–90% | Hard | Threshold, few words |
| 90–100% | Maximal | Short intervals only |
Health guidelines generally recommend at least 150 minutes of moderate activity a week, and many people can get this in the 60–75% range.
If you have heart disease, high blood pressure, take heart-rate-lowering medication (such as beta-blockers) or are new to exercise, check with your doctor before using heart rate targets. Medication can make heart-rate zones misleading.
Resting HR + intensity × (maximum HR − resting HR). For resting 60, max 185 and 70%, the target is about 148 bpm.
Count your pulse for 60 seconds after waking, before getting up, over several mornings, and take the average.
Moderate intensity, around 60–70% of heart rate reserve, is sustainable for longer sessions. Total energy used matters more than the zone.