Heart Rate Calculator
Training zones turn a heart rate monitor from a curiosity into a tool. This calculator estimates your maximum heart rate from age and derives the zone boundaries, so you know which efforts build endurance and which build top-end capacity.
Inputs
Result
190 bpm max
Fat burn 140–153 · Cardio 153–171 bpm
How the heart rate calculator works
Maximum heart rate is estimated as 220 − age, or more accurately by Tanaka: 208 − 0.7 × age.
Zones as a percentage of maximum: Zone 1 50–60% recovery, Zone 2 60–70% aerobic base, Zone 3 70–80% tempo, Zone 4 80–90% threshold, Zone 5 90–100% maximal.
The Karvonen method uses heart rate reserve for more personal zones: target = resting + (max − resting) × intensity.
Worked example: age 40, resting heart rate 58
- Simple max: 220 − 40 = 180 bpm. Tanaka: 208 − 28 = 180 bpm.
- Zone 2 by percentage of max: 108–126 bpm.
- By Karvonen, heart rate reserve is 180 − 58 = 122.
- Zone 2 (60–70% of reserve): 58 + 73 = 131 to 58 + 85 = 143 bpm.
- The Karvonen zones sit meaningfully higher, which is why fit people find percentage-of-max easy zones too easy.
Common mistakes to avoid
Trusting 220 minus age as an individual truth
The formula has a standard deviation of 10–12 bpm, so your real maximum could be 20 bpm either side. A field test is far more useful.
Spending most training in Zone 3
The classic mistake: too hard for easy days, too easy for hard days. Most endurance progress comes from lots of Zone 2 and a little Zone 4–5.
Comparing heart rates between people
Maximum and resting rates are individual. A higher heart rate at the same pace says nothing about fitness relative to someone else.
Frequently asked questions
How do I find my real maximum heart rate?
A supervised graded exercise test, or a hard field test such as three all-out efforts up a long hill. Only do this if you are healthy and cleared for maximal exercise.
What is Zone 2 training?
Sustained easy aerobic work at roughly 60–70% of maximum, where conversation is possible. It builds the aerobic base most endurance improvement rests on.
What does a low resting heart rate mean?
Usually good cardiovascular fitness — trained endurance athletes are often in the 40s. Genetics contributes too.
Does heart rate drift during long efforts?
Yes, cardiac drift raises heart rate at constant pace as core temperature and dehydration increase. Pace-based targets can be more stable for long sessions.
Which zone burns the most fat?
Fat oxidation peaks in Zone 2 as a proportion of fuel, but total calories and therefore fat loss depend on overall energy balance across the week.
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