Heart rate zones calculator

Why zones matter for people with real jobs

If you work on your feet all day, "go hard every session" is how you end up exhausted and injured. Most of your cardio should sit in zone 2 - the pace where you could still talk - because it builds the aerobic base that makes everything else easier and it does not wreck your recovery for the next shift. Zones 4 and 5 are for one or two short, hard sessions a week, not every day.

How the numbers are worked out

Max heart rate is estimated with the Tanaka formula, 208 minus 0.7 times your age, which fits real measurements across adult ages better than the old 220 minus age. If you have a measured max from a test or a hard hill sprint, type it in and the tool uses that instead. If you add your resting heart rate, the zones are calculated with the Karvonen method - a percentage of the gap between resting and max, added back to resting - which gives higher, more realistic zone floors for fit people with low resting rates.

Watches, chest straps and honesty

Wrist sensors are decent at steady efforts and poor at intervals and anything with a lot of arm movement - weights, rowing, site work. A chest strap is the accurate option. And if the number and how you feel disagree, believe how you feel: the talk test is the oldest zone check there is and it still works.

FAQs

What is my max heart rate?

Roughly 208 minus 0.7 times your age (the Tanaka formula). For a 35-year-old that is about 184 bpm. Real values vary by 10 to 15 bpm either way, so a measured max from a hard test is better if you have one.

What heart rate zone burns the most fat?

Zone 2, the easy aerobic zone, uses the highest proportion of fat for fuel - but total calories burned matter more for fat loss than the fuel mix, and harder sessions burn more per minute. Do most of your volume in zone 2 for recovery and consistency, not because of a fat-burning myth.

What is the Karvonen method?

A way of setting zones from your heart rate reserve - the gap between resting and maximum - rather than straight percentages of max. Zone floor = (max - resting) x percentage + resting. It gives more accurate zones for people with a low resting heart rate.

How long should I spend in zone 2?

For general fitness, 2 to 4 sessions of 30 to 60 minutes a week is a common target. Walking briskly, cycling, an incline treadmill or a steady row all work. Shift workers can split it into shorter blocks.