Heart Rate Zone Calculator – Karvonen Training Zones
Estimated Max Heart Rate
-- bpm
Heart Rate Reserve (HRR)
-- bpm
| Zone | %HRR | BPM Range |
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How Heart Rate Zones Work (Karvonen Formula)
Heart rate training zones help you exercise at the right intensity for your goals. This calculator uses the Karvonen formula, which accounts for both your maximum heart rate and resting heart rate to produce more personalized zones than simple percentage-of-max methods.
The Karvonen formula calculates your Heart Rate Reserve (HRR) as Max HR minus Resting HR. Each zone target is then: Target HR = (HRR × % Intensity) + Resting HR. If you don't know your max heart rate, the calculator estimates it using the Fox formula (220 − age), though a lab test or field test gives a more accurate number.
Zone 1 (50–60% HRR) is for warm-ups and recovery. Zone 2 (60–70%) builds aerobic base and fat-burning endurance. Zone 3 (70–80%) improves cardiovascular fitness at tempo pace. Zone 4 (80–90%) is lactate threshold training. Zone 5 (90–100%) is maximum effort for short intervals. Most training plans recommend spending 80% of training time in Zones 1–2 and 20% in Zones 3–5.
Frequently Asked Questions
What is the Karvonen formula?
The Karvonen formula calculates target heart rate zones using your Heart Rate Reserve (HRR), which is Max HR minus Resting HR. The target for each zone is (HRR x desired intensity %) + Resting HR. It is more personalized than simple percentage-of-max methods because it factors in your fitness level via resting heart rate.
How do I find my resting heart rate?
Measure your pulse first thing in the morning before getting out of bed. Count your heartbeats for 60 seconds, or count for 15 seconds and multiply by 4. Do this for several mornings and take the average. A typical resting heart rate for adults is 60-100 bpm, while well-trained athletes may have rates as low as 40-50 bpm.
Is 220 minus age accurate for max heart rate?
The 220-minus-age formula provides a rough estimate with a standard deviation of about 10-12 bpm. A graded exercise test in a lab or a supervised field test gives a much more accurate maximum heart rate.
Which heart rate zone burns the most fat?
Zone 2 (60-70% HRR) uses the highest percentage of fat for fuel. However, higher-intensity zones burn more total calories per minute. For overall fat loss, a mix of Zone 2 endurance and higher-intensity intervals is most effective.