What the Zone 2 Heart Rate Calculator does
This calculator gives your Zone 2 heart rate range - the easy, conversational aerobic zone used for base training - worked out three ways side by side: 60-70% of your maximum heart rate, 60-70% of your heart rate reserve (the Karvonen method, which uses your resting pulse), and Phil Maffetone's MAF 180 formula. It shows where the three agree, explains why they often do not, and turns your weekly training time into a Zone 2 plan.
Most calculators pick one formula and present the result as if it were exact. The methods really do give different answers, by 10 to 20 beats a minute for the same person, because they define the zone differently. Seeing them together, with the working, makes it easier to choose a range you can actually train in. It is an estimate for healthy adults, not medical advice, and nothing you type leaves the page.
How to use it
- Enter your age. Add your resting heart rate - count your pulse for a full minute after waking, before getting up, on a few mornings and take the lowest.
- If you have measured your maximum heart rate in a test or a hard race, enter it; otherwise choose the estimate (Tanaka, 208 - 0.7 x age, or the classic 220 - age).
- Pick the MAF 180 adjustment that describes your health and training history.
- Read the headline range (Karvonen when you have entered a resting pulse) and compare the three bars. A dashed outline marks the band where all methods agree, if there is one.
- Enter your weekly training minutes, the share you want at Zone 2 and the number of sessions to see minutes per week and per session.
Reading the results
Percentage of maximum is the simplest method but ignores fitness: two 40-year-olds get the same range whatever their resting pulse. Karvonen adds your resting rate, so a fitter person with a low resting pulse gets a slightly higher range. MAF 180 is a ceiling rather than a band: train below it, ideally within 10 beats of it.
When the ranges do not overlap, use the talk test: in Zone 2 you can talk in full sentences and breathe through your nose, but singing would be hard. If the number on your watch and the talk test disagree, trust the talk test and adjust.
The weekly plan uses the common 80/20 idea - most training easy, a fifth hard. Zone 2 counts as moderate activity, so the WHO's 150 to 300 minutes a week of moderate exercise is a useful reference point.
This tool covers only Zone 2. For all five training zones from one formula, use the Heart Rate Zone Calculator; this page exists to compare methods for the aerobic base zone in depth.
Worked example: a 40-year-old with a resting pulse of 60
Estimated maximum (Tanaka): 208 - 0.7 x 40 = 180 bpm.
Percentage of maximum: 0.60 x 180 = 108 and 0.70 x 180 = 126, so 108-126 bpm.
Heart rate reserve: 180 - 60 = 120. Then 60 + 0.60 x 120 = 132 and 60 + 0.70 x 120 = 144, so 132-144 bpm.
MAF 180 with no adjustment: 180 - 40 = 140, so train between 130 and 140 bpm. The three ranges do not share a common band (126 is below 132), which is normal. With four sessions and 240 minutes a week at 80% Zone 2, that is 192 minutes of Zone 2, 48 minutes per session.
Formulas and scoring rules
- Maximum heart rate (estimate)
HRmax = 208 - 0.7 x age (Tanaka 2001) or 220 - ageA measured maximum replaces both.- Percentage of maximum
Zone 2 = 0.60 x HRmax to 0.70 x HRmax- Heart rate reserve (Karvonen)
Zone 2 = HRrest + 0.60 x (HRmax - HRrest) to HRrest + 0.70 x (HRmax - HRrest)- MAF 180
ceiling = 180 - age + adjustment (-10, -5, 0 or +5); range = ceiling - 10 to ceiling- Weekly plan
Zone 2 minutes = weekly minutes x share / 100; per session = Zone 2 minutes / sessionsAll heart rates are rounded to whole beats per minute, half away from zero.
Limitations: what the result does not prove
- Age-based maximum heart rates are population averages; individuals commonly differ by 10 beats a minute or more, which shifts every range. A measured maximum is better, and a lab test better still.
- Medicines such as beta blockers, heart conditions, pregnancy, heat, dehydration and caffeine all change heart rate. Anyone in those situations should ask a doctor before training to a heart-rate target.
- Zone 2 is defined physiologically by lactate or ventilatory thresholds, which none of these formulas measures. The ranges are estimates of where that point usually falls.
- Wrist-based heart-rate monitors can read high or low, especially during intervals; a chest strap is more reliable for keeping to a narrow zone.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- WHO guidelines on physical activity and sedentary behaviour (2020)
- Tanaka, Monahan and Seals (2001) - Age-predicted maximal heart rate revisited, JACC
- American Heart Association - Target heart rates
Frequently asked questions
What is my Zone 2 heart rate by age?
By age alone, 60-70% of an estimated maximum: about 112-131 bpm at 30, 108-126 at 40 and 104-121 at 50 with the Tanaka formula. Adding your resting pulse (Karvonen) personalises it, and the tool shows both plus MAF 180.
Why do Zone 2 calculators give different numbers?
They use different definitions: a share of maximum, a share of the reserve above your resting pulse, or an age-based ceiling. For the same person they can differ by 10 to 20 bpm. Comparing them side by side, as here, shows the spread instead of hiding it.
What is the MAF 180 formula?
Phil Maffetone's rule: subtract your age from 180, then take off 10 if you are recovering from illness or on regular medication, take off 5 if you are often injured or ill or training inconsistently, or add 5 after two years of steady progress. Train at or just below that number.
How long should I train in Zone 2 each week?
Endurance coaches often put about 80% of training time at easy intensity. For general health, the WHO recommends at least 150 to 300 minutes of moderate activity a week, and Zone 2 counts towards it. The weekly plan works out the minutes for your schedule.
How do I know I am in Zone 2 without a monitor?
Use the talk test: you should be able to speak in full sentences and breathe comfortably, ideally through your nose, but not sing. If you can only manage a few words, you are above Zone 2.
Is Zone 2 the same as the fat-burning zone?
Roughly. At easy intensities a larger share of energy comes from fat, which is where the name comes from, but total energy use is lower than at higher intensities. Zone 2 is mainly used to build aerobic endurance.
Last reviewed by the A2Z.Tools team against the sources listed above.
