Heart rate zones calculator
At 35, zone 2 is 111–128 bpm by max heart rate and higher if you add a resting rate. All five zones three published ways, each with its error.
Your heart rate zones
Your age alone gives a first answer. Add a resting heart rate or a threshold test result and the zones are built on more of your own data.
zone system
To compare methods, add a resting heart rate or a threshold heart rate.
Zone 2 · % of max HR
111–128bpm
Zone 2 is 60–70% of your max heart rate. It ignores your resting heart rate, so for most runners it reads lowest of the three methods.
| Zone | Heart rate | % of max HR |
|---|---|---|
| 1Recovery | 92–110 | 50–60% |
| 2Easy aerobic | 111–128 | 60–70% |
| 3Steady | 129–147 | 70–80% |
| 4Threshold | 148–165 | 80–90% |
| 5Max | 166–184 | 90–100% |
Max heart rate 184 bpm, estimated with 208 − 0.7 × age. About one runner in three is more than 11 bpm off that line; 220 − age says 185. A measured max beats both.
Not medical advice. If you have a heart condition, take beta blockers or other medicine that changes your heart rate, or are new to exercise, talk to a doctor before training by heart rate. Sources: Edwards (1993), Tanaka et al. (2001), Sarzynski et al. (2013).
Zone 2 is not one number
For a 35-year-old, zone 2 is 111–128 bpm by percent of max heart rate. Add a resting heart rate of 60 and the heart rate reserve method puts it at 135–146 bpm. If a 30-minute threshold test put your threshold heart rate at 165, Friel's method says 141–148 bpm. Same runner, three published methods, up to 18 beats apart at the bottom of the zone.
None of the three is wrong. Each measures intensity against a different reference: your maximum, the gap between your resting and maximum rates, or a heart rate you actually held for half an hour. The more of your own data a method uses, the more it can be trusted, which is why the calculator above leads with the richest method your inputs allow and prints the others beside it.
Most calculators make you pick one method and present its output as your zones. The spread between methods is the honest error bar, and it is usually larger than the difference between zone 2 and zone 3.
Heart rate zones by age
Max heart rate estimated with 208 − 0.7 × age, then the five bands. Find your age, then replace the estimate with a measured max when you have one.
Some zones are hidden at this width. The calculator above shows all five for your age, or turn your phone sideways.
| Age | Max HR |
|---|---|
| 20 | 194 |
| 25 | 191 |
| 30 | 187 |
| 35 | 184 |
| 40 | 180 |
| 45 | 177 |
| 50 | 173 |
| 55 | 170 |
| 60 | 166 |
| 65 | 163 |
| 70 | 159 |
Beats per minute. Max HR is Tanaka et al. (2001), 208 − 0.7 × age, rounded; zones are Edwards’ bands of 50, 60, 70, 80 and 90% of that max. Both age formulas carry a standard error of about 11 to 12 bpm (Sarzynski et al. 2013), so treat a row as a starting point and replace the max with a measured one when you have it.
The three methods, and when each is right
Percent of max heart rate
Five bands of ten percentage points each, from 50% to 100% of your maximum. This is the system Sally Edwards set out in The Heart Rate Monitor Book (Polar, 1993), and Garmin's default zone table still uses it. Zone 2 is 60–70% of max.
It needs only one number, which is its strength and its weakness. It ignores your resting heart rate, so a fit runner with a resting rate of 45 and an unfit one at 75 get the same zones if their max is the same. For most runners it reads lowest of the three. If you only know your age, it is still a reasonable place to start.
Heart rate reserve (Karvonen)
Martti Karvonen and colleagues published the formula in 1957: target heart rate = resting rate + intensity × (max − resting). The gap between max and resting is your heart rate reserve. The calculator applies the same five bands to the reserve, so zone 2 is 60–70% of reserve, added back onto your resting rate.
Because it starts from your own floor, two runners with the same max but different resting rates get different zones, which matches how training actually feels. The American College of Sports Medicine classifies exercise intensity on reserve for the same reason: its 2011 position stand puts moderate intensity at 40–59% of reserve and vigorous at 60–89% (64–76% and 77–95% of max).
Lactate threshold heart rate (Friel)
Joe Friel's running zones are set as a share of your lactate threshold heart rate (LTHR): zone 1 is under 85%, zone 2 is 85–89%, zone 3 is 90–94%, zone 4 is 95–99%, and zone 5 splits into 5a (100–102%), 5b (103–106%) and 5c (over 106%).
LTHR comes from a test, not a formula, so this method has no age estimate in it at all. That makes it the one to trust once you have done the test, and the zones move when your fitness does. Its weakness is the test itself: start too fast and fade, and the number reads low.
Why the methods disagree
There is no single agreed five-zone system. A 2025 survey of 778 endurance coaches and athletes by Seiler-Viken and colleagues found that five zones is the most common scheme, but the boundaries differ between countries and between sports, particularly running and cycling. When two apps give you different zone 2 numbers, they are usually using different methods rather than one of them being broken.
Your max heart rate is probably not 220 minus your age
For most people, 220 minus age is within about 12 beats of their real maximum, and for about one in three it is further off than that. The formula is usually credited to Fox, Naughton and Haskell (1971). Robergs and Landwehr traced its history in 2002 and found it was never derived from original research.
Tanaka, Monahan and Seals (2001) pooled 351 studies covering 18,712 people and found a better fit: 208 − 0.7 × age. The two lines cross at 40. Below 40, 220 − age reads higher; above 40 it reads lower, by 6 beats at 60 and 9 at 70. In a study of 762 adults, the standard error of estimate was 12.4 bpm for 220 − age and 11.4 bpm for Tanaka (Sarzynski et al., 2013).
So both are estimates, and the calculator labels them that way. A measured maximum beats either. If you do not have one, the threshold method avoids the problem entirely, because it never uses your max.
How to measure your own numbers
Resting heart rate
Take it lying down, first thing in the morning, before coffee and before you get up. Average three or four mornings; one reading after a bad night or a coffee can be several beats high.
Lactate threshold heart rate
Friel's test: run 30 minutes alone, as hard as you can hold evenly for the whole time, as if it were a race. Press lap at 10 minutes. Your average heart rate for the last 20 minutes is your LTHR. Do it alone rather than in a race, and expect your pacing to improve if you repeat it.
Max heart rate
The highest reading you see at the end of a genuinely all-out effort, such as the final minutes of a hard 5K, is a usable floor for your max. It is not a test to try if any of the medical caveats below apply to you.
Where zone 2 fits in a training week
Heart rate is one way to keep easy runs easy; pace is the other. If you have a recent race result, the VDOT calculator turns it into easy, threshold and interval paces, and the two usually agree once you are fit. Your max and resting rates also feed the heart rate method in the VO2 max calculator.
Zone 2 does most of its work in volume. The long run is where most runners spend their longest stretch of it, and every half marathon plan on this site is built mostly on easy running with a few harder sessions. In a review of how elite endurance athletes train, Seiler (2010) found roughly 80% of sessions at low intensity.
Put your zones into a half marathon plan
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12-week half marathon plan
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- 22mi
- Whole plan
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Fair questions
How do I work out my zone 2 heart rate?
Pick a method and do the arithmetic. By percent of max, zone 2 is 60–70% of your max heart rate: 111–128 bpm for a 35-year-old using the age estimate of 184. By heart rate reserve, it is resting rate plus 60–70% of (max minus resting): 135–146 bpm for the same runner with a resting rate of 60. By Friel's threshold method, it is 85–89% of the heart rate you held for the last 20 minutes of a 30-minute solo test. The calculator above does all three.
Is 75% of max heart rate still zone 2?
Not by percent of max: 75% is zone 3, which runs from 70% to 80%. By heart rate reserve it can be. For a runner with a max of 184 and a resting rate of 60, 75% of max is 138 bpm, which is 63% of reserve and squarely in zone 2. That is the clearest example of why the method matters more than the label.
What is the aerobic heart rate zone?
It depends on whose zones you use. Sally Edwards' original five-zone system, which most watches copy, calls 70–80% of max the aerobic zone, which is zone 3. Most runners now say aerobic or easy for zone 2, the 60–70% band. Both are aerobic in the physiological sense; the label is a naming choice, not a boundary in your body.
Is a heart rate of 120 OK when exercising?
For many adults 120 bpm is light to moderate exercise. For a 35-year-old with an estimated max of 184 it is 65% of max, which is zone 2. Whether it is right for you depends on your own max and resting rates, not on a single number. This is not medical advice: if you have a heart condition, take medicine that changes your heart rate, or are new to exercise, ask a doctor what range is safe for you.
What is the best heart rate for burning fat?
Zone 2, 60–70% of max, is often sold as the fat-burning zone. At easy intensities a larger share of the energy you use comes from fat, and the share shifts toward carbohydrate as intensity rises (Brooks and Mercier's crossover concept, 1994). Harder running still burns more total energy per minute. For runners the better reason to spend time in zone 2 is volume: in Seiler's 2010 review, elite endurance athletes did about 80% of their sessions at low intensity.
What should my max heart rate be?
Two age formulas give a starting estimate: 220 − age, and Tanaka's 208 − 0.7 × age, which fits large studies better. At 35 they give 185 and 184. Both carry a standard error of about 11 to 12 bpm, so roughly one person in three is further off than that. Your measured max is whatever it is; a higher or lower number is not a sign of fitness on its own.
What is a good resting heart rate?
Mayo Clinic gives 60 to 100 beats per minute as the typical adult range, and notes that well-trained athletes can sit closer to 40. Measure it lying down first thing in the morning and average a few days. A resting rate above 100 is outside the range these zone methods assume; talk to a doctor if that reading is real.
Which heart rate zone method is most accurate?
The one built on the most of your own data. A threshold heart rate from Friel's 30-minute test beats heart rate reserve, which beats percent of max, which is only as good as your max. If your max comes from an age formula, every zone inherits its error of about 11 to 12 bpm. If you can do one test, do the threshold test.
Why does my watch show different zones?
Usually because it uses a different method or a different max. Garmin's default zones, for example, are Edwards' five 10% bands of max heart rate, with a max the watch estimated or detected from your runs. If that max differs from yours by 10 beats, every zone shifts. Garmin can also base zones on heart rate reserve; enter the same max and resting rate here and the two should agree.