What Is Your Max Heart Rate? Three Simple Formulas Compared

Every heart rate zone on your watch is a percentage of one number: your max heart rate. If that number is off, every zone is off with it. Most watches start with a simple age-based formula, and you can do the same math in under a minute. Here is how three common formulas compare and which one makes sense for you.

The Three Formulas

The numbers are beats per minute and rounded. You can plug your own age into our heart rate zone calculator to see the zones each estimate produces.

Why the Formulas Disagree

Each formula came from a different group of people. The classic 220 minus age rule is easy to remember but tends to underestimate max heart rate for older adults. Tanaka was built from a larger pool of data and spreads the decline with age more gently. Gulati was based on women only, so many women find it closer to their real numbers. None of them is exact for any one person. Real max heart rates can differ from the formula by 10 beats or more in either direction.

Worked Example

Take a 45-year-old runner. The classic formula gives 175, Tanaka gives about 177. Zone 2, often set at 60 to 70 percent of max, works out like this:

• Classic: 105 to 123 bpm
• Tanaka: 106 to 124 bpm

At this age the difference is small. At 60, the gap grows to about 6 bpm, which can move an easy run into a harder zone.

How Your Watch Uses Max Heart Rate

Most watches start with an age-based formula, then quietly adjust if they see you reach a higher heart rate during a hard workout. Garmin, Apple, Samsung and others let you type in your own max value manually. Some also offer zones based on heart rate reserve, which uses your resting heart rate as well. That approach often fits fitter people better. Our guide to how optical heart rate sensors work explains where the readings come from.

When to Trust a Measured Number Instead

If you train regularly, look back at your highest heart rate in recent hard efforts, such as the end of an all-out race or a hill sprint. That number is usually a better guide than any formula. Make sure the reading was steady, not a sudden spike caused by a loose strap. If your readings look odd, see why heart rate readings look wrong. Anyone with a heart condition should ask a doctor before doing maximal efforts.

Final Thoughts

Your max heart rate sets every training zone. The classic 220 minus age formula is a fine start, Tanaka often fits adults over 40 a little better, and Gulati often suits women. A measured value from real hard efforts beats them all. Pick a number, enter it in your watch and check your zones with the heart rate zone calculator. For a broader fitness picture, try the VO2 max calculator.

FAQs

Is 220 minus age accurate?

It is a rough estimate. Many people are 10 beats or more above or below it.

Does max heart rate go up with fitness?

Not much. Fitness mainly lowers resting heart rate, while max heart rate drifts down slowly with age.

Should I change the max heart rate on my watch?

Yes, if you have a reliable measured value. It makes every zone more accurate.