Heart Rate Zone Calculator

How this is calculated

The maximum heart rate uses the Tanaka formula: 208 minus 0.7 times your age. It comes from a 2001 meta-analysis of 351 studies covering 18,712 people aged 20 to 86, and it has roughly half the error of the familiar 220 minus age. That older formula - sometimes called the Fox equation - has no real research behind it. It was a convenient line drawn through limited data decades ago and it stuck because it is easy to do in your head. The two formulas CROSS at exactly age 40: setting 220 minus age equal to 208 minus 0.7 times age gives 12 = 0.3 times age, so age 40. Below 40 the old formula reads HIGH, above 40 it reads LOW, and the gap widens in both directions - about 6 beats too high at 20 and about 9 beats too low at 70. The zones use the Karvonen method, which works from your heart rate RESERVE - your maximum minus your resting rate - rather than from a bare percentage of maximum. A zone boundary is your resting rate plus that percentage of the reserve. This matters because two people with the same maximum and very different resting rates are not doing the same work at the same heart rate, and a plain percentage-of-maximum model cannot see that. Get the resting rate right or the zones inherit the error. It means your rate measured on waking, lying still, before getting up or looking at anything. A figure taken sitting at a desk is usually ten to twenty beats higher and will push every zone up with it. ⚠️ ALL age-predicted formulas carry a standard deviation of around 10 to 15 beats per minute. That is not a rounding error - it means your true maximum could reasonably be 15 beats either side of the number here, which is more than the width of a zone. Treat these as a starting range to calibrate against how you actually feel, not as thresholds to obey. A properly conducted field test or a lab test gives a real number; an equation gives a population average. ⚠️ THIS ASSUMES YOU ARE WELL ENOUGH TO TRAIN HARD, AND IT CANNOT CHECK THAT. Zone training deliberately pushes your heart rate high, and an estimated maximum is a population average rather than a measurement of you. Anyone with a heart condition, high blood pressure, chest pain or breathlessness on exertion, anyone on medication that affects heart rate - beta blockers in particular flatten it entirely - and anyone returning after a long break or an illness should get these numbers from a clinician instead of a formula. A zone chart is not a clearance to exercise.

Common questions

What is wrong with 220 minus age?

It has no real research behind it - it was a convenient line drawn through limited data decades ago and survived because it is easy to do in your head. Tanaka's formula came from a meta-analysis of 351 studies and 18,712 people, and carries roughly half the error. The two cross at exactly age 40, so under 40 the old formula reads high and over 40 it reads low: about 6 beats too high at 20, and about 9 beats too LOW at 70. Older athletes are the ones it short-changes most.

Why does it ask for my resting heart rate?

Because the zones use the Karvonen method, which works from your heart rate RESERVE - maximum minus resting - rather than a flat percentage of maximum. Two people with the same maximum and resting rates of 45 and 70 are not doing the same work at 150 beats, and a percentage-of-maximum model cannot tell them apart. Karvonen can, which makes the zones fit the person rather than the age.

How do I measure resting heart rate properly?

On waking, lying still, before you get up, check your phone or think about the day. Count for a full minute, or use a wearable's overnight figure if you have one. Do it several mornings and take the lowest sensible value. A reading taken sitting at a desk is commonly ten to twenty beats higher, and because every zone is built on it, that error propagates into all of them.

How accurate is any of this?

Estimated maxima carry a standard deviation of roughly 10 to 15 beats per minute - which is wider than a single zone. Your true maximum could genuinely be 15 beats either side of the figure shown. That is why these are a starting range to calibrate against feel, not thresholds to obey. If you want a real number rather than a population average, that takes a proper field test or a lab test.

Why is the EASY range the one to write down?

Because it is the one nearly everybody gets wrong, in the same direction. Most recreational endurance training is meant to be genuinely conversational, with only a small share of hard work - and left to feel, people drift upward until every session sits in an unproductive middle that is too hard to recover from and too easy to drive adaptation. Seeing 'easy' as an actual number is usually a surprise, and holding it usually feels too slow at first.

Should I use these zones for every sport?

Not directly. Maximum heart rate is typically several beats lower in cycling than in running, and lower again in swimming, because of body position and how much muscle mass is involved. If you train seriously in more than one, the usual approach is a separate maximum per sport rather than one number applied everywhere.

Is it safe to train to these numbers?

That depends on you, and this cannot tell. The zones come from an ESTIMATED maximum heart rate - a population average, not a measurement of your heart - and zone training deliberately takes you to high intensities. If you have a heart condition, high blood pressure, chest pain or unusual breathlessness on exertion, or you are returning to exercise after a long gap or an illness, get these figures from a clinician rather than a formula. Medication matters too: beta blockers lower heart rate substantially, so an age-based estimate is simply wrong for anyone taking them. Stop and seek advice for chest pain, dizziness or a heart rate that will not settle afterwards - a chart cannot see any of that.

Take it further with AI

Copy this into ChatGPT or Claude with your own numbers filled in. It hands over the figures this calculator worked out, so the answer is built on real arithmetic instead of a guess.

I used the Heart Rate Zone Calculator at https://www.bfcbrilliance.com/tools/heart-rate-zone-calculator.

What I entered:
- Age (years): ___
- Resting heart rate (bpm): ___

What it calculated:
- Estimated maximum (Tanaka): ___
- What '220 minus age' would say: ___
- Your heart rate reserve: ___
- EASY range — from: ___
- — up to: ___

Use those figures as given — they are already worked out, so please don't recalculate or estimate your own. Help me turn them into a plan: what to buy or do, in what order, roughly what it should cost, and the mistakes people most often make with this job.

Keep this general and do not give medical advice — where it matters, tell me what to raise with a clinician.

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