Learn & Understand

The Formula Everyone Uses and No One Should Trust Blindly

“Subtract your age from 220” is the most repeated formula in fitness — printed on gym charts, built into machines, and used to set training zones the world over. It is also crude, approximate, and wrong for a great many people. Understanding where it came from, and its real limitations, is key to training by heart rate wisely.

The Ubiquitous Rule

The idea that maximum heart rate equals 220 minus your age is everywhere. From it flow the training zones that guide countless workouts — percentages of that estimated maximum defining easy, moderate, and hard effort. Because it needs only your age, it is irresistibly convenient, which is exactly why it became the default despite its shaky foundations.

A Rough Origin

The formula was never meant to be precise. It emerged decades ago as a rough approximation fitted loosely to limited data, more a handy rule of thumb than a rigorous finding. Yet its simplicity carried it into universal use, and it hardened into an assumed fact. Its authority comes from repetition, not from accuracy.

The Wide Scatter

The formula's real weakness is variation. Actual maximum heart rates for people of the same age scatter widely — many beats per minute above or below the estimate. Applied to an individual, the formula can be substantially off, placing training zones too high or too low. It describes an average that few people exactly match, so anyone's true maximum may differ considerably.

Beyond the Estimate

Better approaches exist. Refined formulas fit the data more closely, and the Karvonen method incorporates resting heart rate to personalize zones. Best of all is a measured maximum from a supervised test. The lesson is not to abandon heart-rate training but to treat the famous formula as a starting estimate, refined by better methods and, ideally, real measurement.

Setting Your Zones

To compute training zones, use the Heart Rate Zone Calculator or the more personalized Karvonen Target Heart Rate Calculator. Relate zones to aerobic capacity with the VO2 Max Calculator.