What hat size am I? Measure your head, get every size in 10 seconds
You are in the shop. One tag says S/M/L, another 7⅛, a third one 57 cm. Three systems, one head. Without a chart in your head you cannot tell whether the same hat actually fits.
Type your head circumference in centimetres (measured with a soft tape just above the eyebrows) and the calculator lines up everything side by side: generic S-XXL, US fractional inches (6½ to 8) and UK. It also works the other way around: you only know "M" or "size 7" and want to know what that means in cm? Click and the answer is there.
Pick a hat type: beanie, baseball cap, fedora or helmet (bike or motorcycle). Each one has its own quirks, the calculator shows a note under the result with what to watch out for before you buy. There is a separate children's mode with a kids helmet table.
How to use it
- Pick a hat type at the top: beanie, baseball cap, fedora or helmet. This only affects the note under the result, the size table is the same for everyone.
- Switch on "Children's sizes" if you are measuring a kid. A separate kids helmet table will show up, split into XS, S, M, L, XL.
- Choose what you know: head circumference in cm, the generic S-XXL label or the US fractional size. Centimetres are the safest input.
- Type or click a value. For cm use the plus and minus buttons or type a number. For S-XXL and US you click a specific label from the list.
- The result shows all four systems side by side: cm, generic, US and UK. The column you typed in is highlighted.
- Under the headline a neighbouring-size table shows 2 sizes up and 2 down, useful when you are right between two sizes and not sure which way to go.
- Below the table a note about the selected hat type explains what to expect: why a fitted cap has no wiggle room, why a fedora has to fit precisely, when to size up, when to size down.
- Expand "How to measure your head" at the bottom if you are not sure how to hold the tape. Four simple steps.
When this is useful
Six situations where checking the size before clicking "buy" saves you time and money:
- Buying a New Era fitted cap online. A 59FIFTY is a fixed size, not adjustable. You measure your head: 57 cm. The calculator shows US 7⅛, so you order exactly that. Without the calculator you would have guessed 7 (too tight) or 7¼ (too loose).
- Picking a bike helmet for yourself. Five models in the shop, every brand on a different scale. You measure 58 cm: you know to look for L in one brand, M in another. You walk in with a number, not "probably M".
- Sizing a helmet for your child. The reading is 53 cm: you flip on kids mode, you see S (52-55). You know what to ask for and you do not get talked into a "they will grow into it" purchase. A helmet has to fit today.
- Buying a gift from abroad. Someone asks for a cap from the US. They say "size 7¼". The calculator: 58 cm, so L generic. You know what to look for locally if the US shop does not ship overseas.
- Buying a hat for a wedding. The fedora online lists sizes in cm. You check: 56 cm = M. You order without hesitation, because your head will not change between now and next week. Especially useful for premium hats where returns can be slow or partial.
- Checking whether last year's helmet still fits your kid. You bought 52 cm a year ago, now they measure 55 cm. The calculator shows that is already a different band (S to M). The helmet has to be replaced. No compromises here, a helmet that does not fit does not protect.