How it works
The Karvonen method sets training zones as a percentage of your heart rate reserve, the gap between resting and maximum heart rate, then adds your resting rate back. Because it uses your own resting pulse, it fits fitter people better than a plain percentage of max.
Max heart rate is estimated with the Tanaka (208 − 0.7 × age) or classic 220 − age formula unless you enter a measured value. Estimates can be off by 10 to 12 bpm in either direction, so a measured max gives more personal zones.
Moderate and vigorous bands follow American College of Sports Medicine heart-rate-reserve ranges. Some medications, such as beta blockers, change heart rate response. Results are estimates, not medical advice.
Formula
Target HR = (max HR − resting HR) × intensity + resting HR
Questions people ask
What is zone 2 training?
Zone 2 is easy aerobic work, about 60–70% of heart rate reserve here. You can hold a conversation, and it builds endurance with little fatigue, which is why many training plans spend most time there.
How do I find my resting heart rate?
Take your pulse for a full minute right after waking, before getting out of bed, on several mornings and average the results. Many fitness watches also track it.
Why use heart rate reserve instead of percent of max?
Two people with the same max but different resting rates have different usable ranges. Heart rate reserve accounts for that, so the same percentage reflects similar effort for both.