Hat Size Calculator
Convert hat sizes between systems and from head circumference.
Sizing from your head
Hat sizes come in a few systems — a fitted-hat number, small-medium-large, and the underlying head measurement — that do not obviously line up. This converts between them and from an actual head circumference, so you can turn a measurement into the size a particular hat uses.
Enter a size or a head measurement and see the conversion.
Measure where the hat sits
The dependable foundation is head circumference, which every hat size ultimately comes from, so the accurate way to size a hat is to measure around your head with a tape where the hat will actually sit — just above the ears and eyebrows. From that measurement the various size systems follow. A small tip: hats have less give than clothing, so if you are between sizes it is usually better to size up, and an adjustable or stretchy style forgives a measurement that is not exact.
Common questions
How do I measure for a hat?
Wrap a tape around your head where the hat sits — just above the ears and eyebrows — to get the circumference every size is based on.
What if I am between sizes?
Hats have little give, so sizing up is usually safer, or choose an adjustable or stretchy style that forgives an imperfect measurement.
Is anything uploaded?
No. The conversion happens in your browser.