About the MAF Heart Rate Calculator
This MAF heart rate calculator applies Dr Phil Maffetone’s 180 Formula: subtract your age from 180, then adjust the number up or down based on your health and training history. The result is your maximum aerobic function (MAF) heart rate — the ceiling for easy aerobic training — along with the 10-beat training range just below it.
Low-heart-rate or “MAF training” is popular with marathoners, triathletes and beginners who want to build an aerobic base while limiting fatigue and injury risk. Most of your weekly running or riding stays at or below the MAF number, and progress is tracked with a regular MAF test: the pace you can hold at that heart rate should get faster over the months.
The formula is a practical rule of thumb from Maffetone’s coaching, not a laboratory measurement. It deliberately sets a conservative ceiling, so many runners find they must slow down — or walk hills — at first. For athletes 16 and under, Maffetone uses a fixed 165 bpm instead of the formula.
With the default inputs, the maf heart rate (aerobic ceiling) is 140 bpm. Change any value above to recalculate instantly.
How to use the maf heart rate calculator
- 1Enter your age.
- 2Choose the category that best fits your health and training history — if in doubt, pick the lower one.
- 3If you are over 65 and in category (d), optionally add up to 10 beats.
- 4Train most sessions within the 10-beat range below your MAF heart rate.
- 5Repeat a MAF test (e.g. 5 miles at MAF HR on a track) every month to see your pace improve.
Formula and method
Maffetone’s 180 Formula starts from 180 minus your age, then applies one adjustment: subtract 10 if you have or are recovering from a major illness (such as heart disease), operation or hospital stay, take regular medication or are in overtraining burnout; subtract 5 if you are injured, have stalled or regressed, get more than two colds or flu a year, have allergies or asthma, are overfat, are in the early stages of overtraining, or are returning to training; make no change if you have trained consistently for up to two years without those problems; and add 5 if you have trained for over two years while improving and staying injury-free.
If you fit more than one category, Maffetone advises using the lower number. Athletes 16 and under use 165 bpm, and athletes over 65 in category (d) may add up to 10 beats. Training is done in the range from 10 beats below the MAF number up to the MAF number itself.
- age
- Your age in years
- adjustment
- Health and training-history modifier from categories (a)–(d)
Worked examples
40-year-old training consistently
180 − 40 = 140. Category (c) has no adjustment, so the MAF heart rate is 140 bpm and easy training sits between 130 and 140 bpm.
32-year-old returning from injury
180 − 32 = 148, minus 5 for category (b) gives 143 bpm. The training range is 133–143 bpm.
68-year-old experienced, improving athlete
180 − 68 = 112. Category (d) adds 5, and as an athlete over 65 they add another 5 after honest self-assessment, giving a MAF heart rate of 122 bpm.
Frequently asked questions
What is the 180 Formula?+
It is Phil Maffetone’s rule for finding a maximum aerobic training heart rate: 180 minus your age, adjusted by −10, −5, 0 or +5 depending on your health and training history. Training at or below it is meant to build aerobic fitness with little stress.
Why is my MAF heart rate so low?+
The formula is deliberately conservative to keep training fully aerobic. Many runners have to slow down a lot — sometimes walking hills — at first. With consistent training, the pace you can run at the same heart rate usually improves over several months.
How long should I do MAF training?+
Maffetone recommends a base period of at least three months of training only at or below MAF heart rate, continuing as long as your MAF test pace keeps improving. If progress stalls, review sleep, diet and stress before adding intensity.
Is MAF heart rate the same as zone 2?+
They are similar but not identical. Zone 2 is usually defined as a percentage of maximum heart rate or heart rate reserve, or relative to lactate threshold, whereas MAF uses only age and history. For many people, MAF HR falls near the top of zone 2.
What is a MAF test?+
A MAF test is a regular time trial run entirely at your MAF heart rate — for example, 5 miles or 8 km on a track — recording the pace of each mile or kilometre. Doing it monthly under similar conditions shows whether your aerobic base is improving.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.