To determine out your cap size, measure the circumference of your head with a tape measure about a half-inch above your eyebrows. Use a string if you don’t have a tape measure, and measure that against a ruler. Once you have your measurement, use the chart below to find your cap size.
Sizing charts are a reference not a rule of thumb. Each brand will vary in fit and size (and sometimes cap to cap). Always be sure to try on a fitted baseball cap before you purchase it.