Heart rate zone calculator: your five zones, and where zone 2 sits

Heart rate zones split effort into bands, from easy to all-out, as shares of your max heart rate. Enter your age for an estimated max and five zones in beats a minute, with zone 2 marked; add a measured max or a resting heart rate if you have them.

Find your heart rate zones

The calculator needs JavaScript, which looks to be switched off. The numbers here are the worked example, for a 30-year-old with a resting heart rate of 60, and the method below works by hand.

What the zones are, and where the numbers come from

The five zones come from one national Olympic federation's scale, used by its elite endurance athletes for the last two decades.¹ It hangs on two thresholds: zones 1 and 2 sit below the first, zone 3 between the two, and zones 4 and 5 above the second.² That puts zone 2 just under the first threshold, where an expert panel placed it,³ at 72 to 82% of max.⁴ Published versions print the edges a point apart (73 to 82% for zone 2 in one),¹ so the calculator shares each edge between the two zones it separates. The percentages come from highly trained athletes, and a 2025 survey paper warns they likely overestimate the threshold range for beginners and recreational athletes. In its survey of 710 people active in endurance sport, five zones was the most common layout (47%), and where the edges sat differed between regions and sports.²

The second table adds the general bands. A 2021 paper on intensity terms lists moderate exercise as 64 to 76% of max, or 40 to 59% of heart rate reserve, which is your max minus your resting heart rate.⁵ The reserve method adds that share of the gap to your resting rate: with a max of 187 and a resting rate of 60, the reserve is 127, and 40% of it on top of 60 is 111. The same paper marks the top of moderate at the first threshold,⁵ so zone 2 is the top end of that band. Zone 2 cardio works through the same three ranges.

The talk test asks whether you can speak comfortably;⁶ the point where the answer turns uncertain reflects the first threshold, and the point where it turns to no reflects the second.⁷

Why age formulas miss

Both formulas give the average max for an age, and people scatter widely around it. The 208 minus 0.7 times age equation came from a meta-analysis of 351 studies and 18,712 people.⁸ The older 220 minus age traces to a 1971 paper and wasn't based on regression analysis.⁹

In 762 inactive adults whose max was measured on an exercise bike, the standard error of the estimate was 11.4 beats a minute for 208 minus 0.7 times age and 12.4 for 220 minus age, and some single estimates were 40 or more beats off.⁹ In 4,375 endurance athletes reporting the highest heart rate they had recorded, both formulas came out about 5 beats low on average, with individuals spread widely either side.¹⁰

An 11-beat miss in your max moves zone 2 by 8 or 9 beats, about half the zone's width. Hence the typical miss under the estimate, and the talk test's last word.

How to find your real max without a lab

A max you've reached beats any formula. The study of 4,375 athletes defined a field max as the highest heart rate recorded during maximal training or racing efforts, and its authors note that long warm-ups and repeated maximal efforts bring out higher readings, while built-up fatigue lowers them.¹⁰ Make it a training session, not an exam:

1. Test where you train. Use the cardio you'll do zone 2 on, since max heart rate depends on the conditions it's measured in,¹⁰ and wear a chest strap if you have one.
2. Pick a fresh day, not one after a hard session.
3. Warm up for 15 to 20 minutes, easy, then building.
4. Do three hard efforts of about 3 minutes, with 2 or 3 easy minutes between, each a little harder than the last. Finish the third as hard as you can hold.
5. Take the highest reading, ignoring a spike that doesn't match the effort, and enter it above as your measured max.

No test day? Your highest reading from recent races or hard interval sessions does the same job.

If you have any reason to check with a doctor before an all-out effort, do that first, or skip the test and train from the estimate and the talk test.

How to use zone 2 beside lifting

Use the zone 2 range as the ceiling for easy cardio, and the talk test as the check: if a full sentence isn't comfortable, ease off. How many minutes a week, and how to keep each machine in zone 2, is on zone 2 cardio. Whether it goes before or after lifting, and how much it costs your lifting, is on cardio and lifting.

Rerun the numbers every month or two. As training changes your fitness, the boundaries between intensities move,⁵ and resting heart rate tends to sit lower in people who train more hours a week.¹⁰

What the calculator is not

It isn't a fitness test. It doesn't estimate a fitness level, and a high or low max isn't a score: in the meta-analysis, max heart rate was largely predicted by age and didn't depend on how active people were.⁸

It isn't health advice or a medical test. The zones are for planning training effort. You may see a low zone labelled the "fat-burning zone". On this site that isn't a training target, and no zone here comes with a promise about your body.

Questions

Why does a watch show different zones?

Usually a different max or different edges. Every zone is a share of a max, so check which max the watch uses and enter it here, or put your measured max in both. Then compare the edges, which vary between scales.² If they still disagree, go by the talk test.

Chest strap or wrist sensor: which reads better?

A chest strap, when it matters. In 50 adults on a treadmill, a bike and an elliptical, an electrode chest strap agreed with an ECG better than any wrist or forearm sensor, and the optical sensors' accuracy varied with the exercise: best on the treadmill, worst on the elliptical.¹¹ In 28 adults, arm-worn optical sensors were accurate at rest and in steady, graded exercise, and least accurate in short, high-intensity, full-body moves such as burpees.¹² For steady zone 2 on a treadmill, a wrist reading is often close enough. For a max test, or on a bike or an elliptical, use a strap.

Why do the two formulas give different numbers?

They fall at different rates. 220 minus age drops one beat a year; 208 minus 0.7 times age drops 0.7 a year from a lower start, so they meet at 40, where both give 180. Under 40, 220 minus age gives the higher number; over 40, the newer equation does, and its authors found the old one underestimates max heart rate in older adults.⁸ Up to the late 70s, though, the gap between the two is smaller than either one's typical miss.⁹

The zones are the easy part. If you'd rather have the cardio and the lifting planned together around your week, apply here.