At 40, Zone 2 is 108–125 beats per minute
Heart rate zones split your effort during exercise into five bands, each defined as a percentage of your maximum heart rate. The sports watch maker Polar sets Zone 1 (very light) at 50–60% of max, Zone 2 (light) at 60–70%, Zone 3 (moderate) at 70–80%, Zone 4 (hard) at 80–90% and Zone 5 (maximum) at 90–100%. For a 40-year-old, the Tanaka equation (208 − 0.7 × age) puts max heart rate at 180 bpm. That makes Zone 2 108–125 beats per minute and Zone 3 126–143.
Enter your age and this calculator shows all five zones as bpm ranges. Add a resting heart rate and it also splits the zones with the Karvonen (heart rate reserve) method. You can compare five max heart rate formulas side by side, or type in a max you measured in a stress test or all-out effort. Enter your current heart rate to see which zone you are in, and see what "moderate" and "vigorous" in the ACSM intensity table mean in bpm for you. The heart and ECG trace beat at the middle rate of the zone you select, so you can get a feel for the pace.
Why measure exercise intensity by heart rate
The World Health Organization's 2020 guidelines recommend that adults do 150–300 minutes of moderate-intensity or 75–150 minutes of vigorous-intensity aerobic activity per week, or an equivalent combination. But the same walking pace can be moderate for one person and an easy stroll for another. Heart rate shows how hard your body is working right now, so it is one of the simplest ways to turn "moderate" into a number that fits you.
Typical times to use it:
- Starting an exercise routine: check whether brisk walking or cycling reaches the moderate range, and which beats-per-minute figure you need to stay above.
- Setting up the zones on a sports watch: if your watch zones are based on a max heart rate estimated from age, enter a measured max or resting rate here, recalculate the zones, and use the result to correct the watch settings.
- Easy Zone 2 runs: compare your recorded heart rate with the Zone 2 range to see whether an easy day stayed easy or drifted into Zone 3 or 4.
- Hiking, swimming and cycling: when pace or distance says little about effort, heart rate shows how hard the session really was.
A heart rate number is still an estimate. The ACSM intensity table in the guide section below pairs each intensity level with a perceived-exertion rating (RPE), so check how hard it feels alongside the number on your wrist.
How to use it
- Enter your age in years. Age is the only input the formulas need, so this alone gives the five zones.
- Enter your resting heart rate (optional). The American Heart Association says to check it in the morning after a good night's sleep, before you get out of bed or have that first cup of coffee. With it, a heart rate reserve line appears and you can choose the Karvonen basis.
- Choose the zone basis. "% of max heart rate" is the method Polar uses for its five zones. "% of heart rate reserve (Karvonen)" also takes your resting rate into account.
- Under max heart rate formula, pick a formula, or enter a measured value under "Measured value". The dot row shows how far apart the formulas land.
- Tap a zone on the ladder to see its range, the arithmetic and the pulse count in the monitor panel with the beating heart. Enter the current heart rate from your watch and the marker moves to the zone you are in. Copy the result, copy a link that holds your inputs, or save the zones as an image.
How the numbers are calculated
1. Estimating max heart rate
Max heart rate is the highest number of times your heart can beat in a minute during all-out effort. The only precise way to learn it is a maximal exercise test, so most people estimate it from age. The table shows each formula at age 40. The calculator rounds the result to the nearest whole bpm.
| Formula | Equation | Result at age 40 | Max heart rate (bpm) |
|---|---|---|---|
| Tanaka 2001 | 208 − 0.7 × age | 180 | 180 |
| Fox 1971 (common) | 220 − age | 180 | 180 |
| Gellish 2007 | 207 − 0.7 × age | 179 | 179 |
| Nes 2013 | 211 − 0.64 × age | 185.4 | 185 |
| Gulati 2010 (women) | 206 − 0.88 × age | 170.8 | 171 |
2. Splitting into zones: % of max and Karvonen
The % of max heart rate method multiplies max heart rate by each zone's percentages. At age 40 (max 180 bpm), Zone 2 starts at 180 × 60% = 108 and ends just below 180 × 70% = 126. The Karvonen (heart rate reserve) method, which goes back to Karvonen and colleagues in 1957, subtracts resting heart rate from max to get the reserve, multiplies the reserve by the percentage and adds the resting rate back. With a resting rate of 64 bpm the reserve is 180 − 64 = 116 bpm, and Zone 2 starts at 64 + 116 × 60% = 133.6.
When a boundary is not a whole number, the calculator starts the zone at the first whole bpm at or above it and ends it one beat before the next zone starts. So 133.6 becomes 134 bpm, and the top of Zone 5 is the max itself. This keeps the percentages on screen consistent with the zone a given heart rate falls into. The same person gets quite different ranges depending on the basis.
| Zone | Percent | % of max heart rate (bpm) | % of heart rate reserve, Karvonen (bpm) |
|---|---|---|---|
| Zone 5 | 90–100% | 162–180 | 169–180 |
| Zone 4 | 80–90% | 144–161 | 157–168 |
| Zone 3 | 70–80% | 126–143 | 146–156 |
| Zone 2 | 60–70% | 108–125 | 134–145 |
| Zone 1 | 50–60% | 90–107 | 122–133 |
With Karvonen, the resting rate acts as a floor, so the lower zones sit higher. Within a zone, the gap between the two methods equals resting rate × (1 − the zone percentage), so the higher your resting heart rate, the bigger the gap. When you set up a sports watch, check which basis it uses before comparing zones.
Heart rate zones by age
Ranges in bpm, using Tanaka max heart rate and the % of max heart rate basis. To factor in your resting heart rate, choose the Karvonen basis in the calculator above.
| Age | Max | Zone 1 50–60% | Zone 2 60–70% | Zone 3 70–80% | Zone 4 80–90% | Zone 5 90–100% |
|---|---|---|---|---|---|---|
| 20 | 194 | 97–116 | 117–135 | 136–155 | 156–174 | 175–194 |
| 30 | 187 | 94–112 | 113–130 | 131–149 | 150–168 | 169–187 |
| 40 | 180 | 90–107 | 108–125 | 126–143 | 144–161 | 162–180 |
| 50 | 173 | 87–103 | 104–121 | 122–138 | 139–155 | 156–173 |
| 60 | 166 | 83–99 | 100–116 | 117–132 | 133–149 | 150–166 |
| 70 | 159 | 80–95 | 96–111 | 112–127 | 128–143 | 144–159 |
What moderate and vigorous mean in bpm
The American College of Sports Medicine (ACSM) position stand (Garber et al., 2011) classifies exercise intensity as follows.
| Intensity | Heart rate reserve (%HRR) | Max heart rate (%HRmax) | Perceived exertion (RPE) |
|---|---|---|---|
| Very light | under 30% | under 57% | under 9 |
| Light | 30–39% | 57–63% | 9–11 |
| Moderate | 40–59% | 64–76% | 12–13 |
| Vigorous | 60–89% | 77–95% | 14–17 |
| Near-maximal | 90% or more | 96% or more | 18 or more |
For a 40-year-old with a resting rate of 64 bpm, moderate and vigorous work out as below. The calculator reads 64–76% as whole-percent steps, from 64% up to just under 77%, so a current heart rate shown as 76% of max is always marked moderate. The weekly amounts, 150–300 minutes at moderate or 75–150 minutes at vigorous intensity, come from the WHO 2020 guidelines.
| Intensity | % of max heart rate | Age 40 (bpm) | % of heart rate reserve | Age 40, resting 64 (bpm) |
|---|---|---|---|---|
| Moderate | 64–76% | 116–138 | 40–59% | 111–133 |
| Vigorous | 77–95% | 139–172 | 60–89% | 134–168 |
The American Heart Association gives lower target ranges: moderate-intensity activity at about 50–70% of max heart rate and vigorous activity at about 70–85%. Its chart lists 100–170 bpm for age 20 (max 200), 93–157 for age 35 (max 185) and 85–145 for age 50 (max 170). Organizations draw the lines in slightly different places, so treat any single number as a guide and pair it with how the effort feels.
How accurate is 220 − age?
The familiar 220 − age was not built from a proper study. Robergs and Landwehr (2002) traced it back to Fox and colleagues (1971), and found that Fox did not derive it from original research. It rests on roughly 35 data points and no regression. When the authors ran a regression on those same points, the standard error was 21 beats per minute.
Equations from larger datasets followed. Tanaka and colleagues (2001) pooled 351 studies and 18,712 people to get 208 − 0.7 × age, then checked it in a laboratory study of 514 people aged 18–81. They concluded that 220 − age underestimates max heart rate in older adults. Gellish and colleagues (2007) analyzed 908 maximal tests on 132 people over 25 years and arrived at 207 − 0.7 × age. Nes and colleagues (2013) studied 3,320 healthy adults in the HUNT study and found 211 − 0.64 × age, with a standard error of estimate of 10.8 bpm. Gulati and colleagues (2010) studied 5,437 women without symptoms and found 206 − 0.88 × age, reporting that the traditional calculation, built on men, overestimates women's max heart rate.
| Age | 220 − age | Tanaka | Gellish | Nes | Gulati (women) |
|---|---|---|---|---|---|
| 20 | 200 | 194 | 193 | 198 | 188 |
| 30 | 190 | 187 | 186 | 192 | 180 |
| 40 | 180 | 180 | 179 | 185 | 171 |
| 50 | 170 | 173 | 172 | 179 | 162 |
| 60 | 160 | 166 | 165 | 173 | 153 |
| 70 | 150 | 159 | 158 | 166 | 144 |
As the table shows, 220 − age is 6 bpm above Tanaka at age 20, equal at 40 and 9 bpm below at 70. The gap between individuals is larger than the gap between formulas. Use the formula value as a starting point, and use a measured value if you have one.
Common mistakes
- Treating Zone 2 as "the fat-burning zone": in 18 moderately trained cyclists, Achten and colleagues (2002) found that fat oxidation peaked at 74 ± 3% of max heart rate, which falls inside Zone 3, and it differed from person to person.
- Measuring resting heart rate at a random time: after coffee or right after moving around, the reading runs high and pushes the Karvonen zones up. The American Heart Association says to check it in the morning after a good night's sleep, before getting out of bed or having that first cup of coffee.
- Assuming a watch with different zones is broken: whether a watch uses 220 − age or Karvonen changes what its Zone 2 covers. Match the basis first, then compare.
- Panicking when you pass the formula's max: the formula gives an average, and many people's true max is higher. If your watch reads correctly, enter that figure as a measured value. Stop at once, though, if you have chest pain, dizziness or unusual shortness of breath.
- Treating 220 − age as a measurement: it is a rough rule of thumb with no regression behind it. Where the formulas disagree, the spread you see in the dot row is real uncertainty.
Limits
- Max heart rate formulas describe group averages. Even the Nes equation had a standard error of estimate of 10.8 bpm, so your own value can differ by more than 10 bpm.
- The five zones at 50–100% follow the sports watch convention used by Polar. They can differ from personal zones set by lactate or ventilatory threshold testing.
- The formulas come from adult data, and the Tanaka laboratory validation covered ages 18–81. Treat results outside that range as a rough guide.
- The American Heart Association notes that some drugs and medications affect heart rate, so you may have a lower maximum heart rate and target zone. If you have a heart condition or take medication, set your target heart rate with your doctor.
- The result is not a medical diagnosis. Stop if you feel unwell during exercise and talk to a clinician.
As of 2026-10-19: the formulas, study results, ACSM intensity table, WHO and American Heart Association guidance and Polar zone definitions were checked against the sources below on that date. The numbers in the tables are this calculator's results; age 40 with a resting rate of 64 bpm is an example.
Sources
- 01Tanaka H et al. — Age-predicted maximal heart rate revisited (J Am Coll Cardiol, 2001)351 studies, 18,712 people: 208 − 0.7 × age; lab validation in 514 people aged 18–81
- 02Gellish RL et al. — Longitudinal modeling of the relationship between age and maximal heart rate (Med Sci Sports Exerc, 2007)132 people, 908 maximal tests over 25 years: 207 − 0.7 × age
- 03Gulati M et al. — Heart rate response to exercise stress testing in asymptomatic women (Circulation, 2010)5,437 women without symptoms: 206 − 0.88 × age
- 04Nes BM et al. — Age-predicted maximal heart rate in healthy subjects: The HUNT fitness study (Scand J Med Sci Sports, 2013)3,320 healthy adults: 211 − 0.64 × age, standard error 10.8 bpm
- 05Robergs RA, Landwehr R — The surprising history of the "HRmax = 220 − age" equation (J Exerc Physiol Online, 2002)Where 220 − age comes from (Fox 1971) and the lack of any regression
- 06Garber CE et al. — ACSM Position Stand: Quantity and quality of exercise (Med Sci Sports Exerc, 2011)Intensity classification: %HRR, %HRmax and RPE
- 07Karvonen MJ, Kentala E, Mustala O — The effects of training on heart rate; a longitudinal study (Ann Med Exp Biol Fenn, 1957)The starting point of the heart rate reserve (Karvonen) method
- 08Achten J et al. — Determination of the exercise intensity that elicits maximal fat oxidation (Med Sci Sports Exerc, 2002)18 moderately trained cyclists: maximal fat oxidation at 74 ± 3% of max heart rate
- 09Bull FC et al. — World Health Organization 2020 guidelines on physical activity and sedentary behaviour (Br J Sports Med, 2020)Adults: 150–300 min of moderate or 75–150 min of vigorous aerobic activity per week, or an equivalent combination
- 10American Heart Association — Target Heart Rates Chart (last reviewed 2024-08-12)Max heart rate about 220 − age, target 50–85%, resting 60–100 bpm, pulse counted for 30 seconds × 2, effect of medications
- 11Polar — Heart rate zonesFive zones at 50, 60, 70, 80, 90 and 100% of max heart rate
Frequently asked questions
What heart rate is Zone 2?
Zone 2 is 60–70% of max heart rate. At age 40, the Tanaka max of 180 bpm gives 108–125 beats per minute, and 220 − age (also 180) gives the same range. With a resting heart rate of 64 bpm, the Karvonen method moves it up to 134–145.
Can I just use 220 − age for max heart rate?
It works for a quick estimate, but it was not derived by regression from a proper study. Tanaka et al. (2001) pooled 351 studies to get 208 − 0.7 × age, and found that 220 − age underestimates max heart rate in older adults. At 70, 220 − age gives 150 bpm and Tanaka gives 159. A value from an exercise stress test is more accurate than any formula.
Should I use Karvonen or % of max heart rate?
Karvonen (heart rate reserve) takes your resting heart rate into account as well as your max. The ACSM intensity table gives both bases. To compare with a sports watch, pick the same basis the watch uses. At 40 with a resting rate of 64 bpm, Zone 2 is 108–125 on % of max but 134–145 on Karvonen, a big difference.
When and how do I measure resting heart rate?
The American Heart Association says to check it in the morning after a good night's sleep, before you get out of bed or have that first cup of coffee. Place the tips of your first two fingers on the inside of your wrist, thumb side, count for 30 seconds and multiply by 2. The AHA considers 60–100 bpm normal for most adults.
Is there a fat-burning heart rate zone?
Fat use peaks at some intensity, but it varies between people. In 18 moderately trained cyclists, Achten et al. (2002) found the peak at 74 ± 3% of max heart rate on average, which falls inside Zone 3.
How much exercise should I do per week?
The WHO 2020 guidelines recommend 150–300 minutes of moderate or 75–150 minutes of vigorous aerobic activity per week for adults, or an equivalent combination. At 40, moderate is 64–76% of max heart rate, or 116–138 bpm, and vigorous is 77–95%, or 139–172 bpm.
My heart rate went above my calculated max. Is that a problem?
The formulas give averages, so many people's true max is higher. Even the Nes et al. (2013) equation had a standard error of 10.8 bpm. If your watch reading is not a measurement error, enter it under 'Measured value' to recalculate the zones. If it comes with chest pain, dizziness or unusual shortness of breath, stop and talk to a clinician.
Do medications change my heart rate zones?
They can. The American Heart Association notes that some drugs and medications affect heart rate, so you may have a lower maximum heart rate and target zone. If you have a heart condition or take medication, set your target heart rate with your doctor.