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Maximum Aerobic Function (MAF) Calculator

Calculate your Maffetone 180 Formula MAF heart rate ceiling for aerobic base building. Applies the 5 health and training status adjustments and gives you a training zone, MAF test protocol, and aerobic base plan.

Your details

MAF training ceiling (180 Formula)

145 bpm

Base (180 minus age)
145 bpm
Health adjustment
no adjustment
Resting HR
60 bpm
Heart rate reserve
85 bpm

Maximum aerobic training zone

135 to 145 bpm

The 10 bpm band below the MAF ceiling. Hold every aerobic session inside this range for base building.

Adjustment rationale

Training consistently at least four times per week for up to two years without injury, regression, or recurring illness uses 180 minus age with no adjustment.

Aerobic base building

Train every aerobic session at or below the MAF ceiling for 3 to 6 months. That means easy runs, bike rides, swims, and conditioning work all stay capped; if HR drifts above the ceiling, walk or coast until it drops back. The aim is a deep aerobic base before any tempo or interval work returns to the schedule.

MAF test protocol

Run the same 5K route (or any fixed 3 to 5 mile distance) once a month at or just below your MAF ceiling. Log splits and total time. A faster time at the same heart rate is the objective marker of aerobic improvement. A slower time signals overtraining, illness, poor sleep, or that the ceiling needs the 5 bpm subtraction.

Context

The 180 Formula was developed by Dr. Phil Maffetone in the early 1980s while coaching endurance athletes. It powered Mark Allen to 6 Ironman world titles and is widely cited by Boston Marathon top finishers, ultrarunners, and trail coaches. Peer-reviewed validation is limited, so treat the bpm target as a personalized starting point, not a physiologically exact threshold. Lactate or ventilatory threshold testing is the lab-grade alternative.

MAF Heart Rate Examples

The Maffetone 180 Formula starts with 180 minus age, then applies the health and training adjustment selected in the calculator.

AgeBase 180 formulaMinus 5 adjustmentPlus 5 adjustment
20160 bpm155 bpm165 bpm
30150 bpm145 bpm155 bpm
40140 bpm135 bpm145 bpm
50130 bpm125 bpm135 bpm
60120 bpm115 bpm125 bpm

MAF is a training heuristic. Get clinical advice before using heart-rate targets if you have cardiovascular symptoms or a medical condition.

Frequently Asked Questions about the Maximum Aerobic Function (MAF) Calculator

Where does the Maffetone 180 Formula come from?
Dr. Phil Maffetone developed the 180 Formula as a simple field method for setting a heart-rate ceiling without laboratory testing. It starts with 180 minus age and applies the calculator's health and training-history adjustments. The result is a training estimate, not a measurement of ventilatory threshold, lactate threshold, fat oxidation, or medical fitness.
Why does training below MAF for months actually build aerobic fitness?
Low-to-moderate endurance work can support aerobic adaptations, but the 180 Formula does not establish an individual's threshold or predict a fixed response. Pace at a given heart rate can also change with heat, terrain, fatigue, hydration, equipment, and measurement error. Use repeated sessions only as personal training context, not as proof of a physiological change.
What is the MAF test and how do I track progress?
A MAF test repeats a similar route or indoor session at or below the calculator's heart-rate estimate, then compares pace or power over time. Keep route, conditions, device, and effort as similar as possible. A single slower result does not identify overtraining, illness, nutrition problems, or a need to change the formula.
Is the 180 Formula scientifically validated?
Not as an individual threshold test. The formula is a coaching heuristic, and it does not replace a measured ventilatory or lactate threshold. Evidence for low-intensity endurance training does not validate 180 minus age or its adjustments for every person. Treat the result as an optional starting estimate rather than a physiologically exact boundary.
How do I actually use MAF in an endurance training plan?
The calculator provides a heart-rate estimate only. It cannot design a training plan, determine exercise clearance, or identify an appropriate intensity mix. If you choose to use its result, compare it with perceived effort and stop for chest pain, faintness, unusual breathlessness, or other concerning symptoms. A qualified coach or clinician can help tailor training to your goals and health context.

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