How to measure April 25, 2026 6 min read

How to Measure Your Head for a Hat (All Brands, All Styles)

One number. One minute. Works for every hat in every style across every brand. Includes the US/UK/EU conversion chart and how the same head measurement maps to fitted caps, beanies, cowboy hats, fedoras, and bucket hats.

You order a fitted cap online. It arrives. It sits on top of your head like a circus prop. Or it squeezes your temples so tight you get a headache after 20 minutes.

Hat sizing is broken because nobody learns it. We grow up wearing one-size-fits-all baseball caps with adjustable straps, and then suddenly we are buying fitted caps, beanies, cowboy hats, or wedding hats with actual sizes and we have no idea what those numbers mean.

Here is the truth: hat sizing is the simplest of all clothing measurements. One number. One minute. Works for every hat in every style across every brand.

This guide covers exactly where to measure your head, the conversion between every hat sizing system in use, and how the same head measurement maps to different sizes across fitted caps, beanies, cowboy hats, fedoras, and bucket hats.

What Hat Size Actually Measures

Hat size is the circumference of your head measured at the spot where the hat sits.

That spot is roughly half an inch to one inch above your eyebrows, going around your head at the widest point above your ears.

Three sizing systems exist worldwide:

US fitted hat sizes use numbers like 6 7/8, 7, 7 1/8, 7 1/4. These are head diameter in inches.
UK fitted hat sizes are the same numbers minus 1/8. A US 7 is a UK 6 7/8.
European hat sizes use head circumference directly in centimeters: 56, 57, 58, 59, 60, 61, etc.

The chart further down converts between all three.

What You Need

A soft fabric measuring tape, or
A piece of string and a ruler.

If you are using string, wrap it around your head, mark the overlap, and lay it flat against the ruler. Done.

How to Measure Your Head for a Hat

Five steps. Total time: one minute.

Take any hat or accessory off your head

Smooth your hair flat. Long hair should be down, not in a bun, since you will wear hats over loose hair.

Place the tape on your forehead

Half an inch above your eyebrows.

Wrap the tape around your head

Going above your ears, around the widest part of the back of your skull.

Keep the tape horizontal

Bring it back to the front. The tape should form a ring parallel to the floor — not tilted.

Pull snug and read

Where the tape overlaps. Write it down in both inches and centimeters.

Measure twice. If the numbers match, you have your size. If they do not, measure a third time.

US / UK / EU Hat Size Conversion Chart

Head Circumference	Head (cm)	US Size	UK Size	EU Size
21"	53 cm	6 5/8	6 1/2	53
21 1/4"	54 cm	6 3/4	6 5/8	54
21 5/8"	55 cm	6 7/8	6 3/4	55
22"	56 cm	7	6 7/8	56
22 3/8"	57 cm	7 1/8	7	57
22 3/4"	58 cm	7 1/4	7 1/8	58
23 1/8"	59 cm	7 3/8	7 1/4	59
23 1/2"	60 cm	7 1/2	7 3/8	60
23 7/8"	61 cm	7 5/8	7 1/2	61
24 1/4"	62 cm	7 3/4	7 5/8	62
24 3/4"	63 cm	7 7/8	7 3/4	63

The most common adult head sizes in the US fall between 7 and 7 3/8. If your number falls between two listed sizes, round up. Hats are easier to pad than to stretch.

Hat Style Guide: How the Same Head Fits Different Hats

Different hat styles use the same head measurement but in different ways.

Fitted baseball caps and 59FIFTY-style caps

Use the US size from the chart directly. A 22 3/8 inch head is a US 7 1/8 fitted cap. No ease, no adjustment. The cap should sit snug on your head with no shifting and no headache. If between two sizes, size up. A slightly loose fitted cap can be padded with a foam insert. A tight cap cannot be loosened.

Snapbacks and adjustable caps

These ignore the chart. Most snapbacks fit head circumferences from 21 to 23 inches with strap adjustment. If your head is over 23 inches, look for "big head" or "XL" snapbacks specifically labeled for larger sizes.

Beanies and knit caps

Sized in S, M, L. Stretchy materials make these forgiving:

S: 21 to 22 inches (53 to 56 cm)
M: 22 to 23 inches (56 to 58 cm)
L: 23 inches and up (58+ cm)

If a beanie label says "one size fits all," your head better be 22 to 22.5 inches. Anything outside that range and "one size" stops fitting.

Cowboy hats and dress hats

Use the US size from the chart, identical to fitted caps. Cowboy hats are typically structured felt or straw and have zero stretch. Size up if between sizes. Some brands (Stetson, Resistol) offer "long oval" and "round oval" shapes alongside standard sizes — if your head is more oval than round, the long oval shape will fit better at the same size.

Bucket hats and sun hats

Usually sized in S, M, L:

S: under 22 inches (under 56 cm)
M: 22 to 23 inches (56 to 58 cm)
L: 23 inches and up (58+ cm)

Bucket hats are usually unstructured and forgiving. The "right" size sits with the brim about an inch above your eyebrows.

Fedoras and wide-brim hats

Use the US size or the EU centimeter size directly. These hats have rigid bands and no stretch. Size up if between sizes. If you fall right between two sizes consistently, look into adjustable hat sizers (foam strips you place inside the band) for a custom fit.

Berets

Often labeled in S, M, L or as "one size." Berets have soft, stretchy bands and almost always fit a 22 to 23 inch head without trouble. If your head is under 21 or over 24, look for size-specific berets.

Helmet sizes (bikes, motorcycles, skiing)

Helmets use the same head measurement but with stricter tolerances. A loose helmet does not protect you. Use the head circumference number and the helmet manufacturer's specific chart. Do not size up a helmet.

Five Mistakes That Wreck Your Hat Measurement

Measuring over hair

Long hair worn up, thick hair in a bun, or a hat already on your head adds 0.5 to 1 inch easily.

Tape tilted

Always parallel to the floor. A diagonal tape reads bigger than the real number.

Tape too high or too low

Half an inch above the eyebrows, going around the widest part. Higher and you measure a smaller circumference than the hat will sit at.

Pulling too tight

The tape should be snug. Hats sit on, not crush. A tight tape gives you a hat that pinches.

Trusting "one size fits all"

It usually fits 22 to 22.5 inches. Outside that range, size-specific hats are a must.

When to Size Up vs. Size Down

Default is size up. Hats are easier to pad than to stretch.

Exceptions:

Fitted caps and structured hats: always size up if between two sizes.
Stretchy beanies and slouchy hats: size in the middle. Stretch handles either way.
Helmets: use exact size. Never size up.

FAQs

My head is between two sizes. What do I do?

Size up. Pad with a foam strip if needed.

Does hair thickness affect my hat size?

Slightly. Most people measure with hair down at normal volume. If you have very thick or very long hair you wear up, measure both ways and use the larger number for occasion-specific hats.

Why does my hat fit at first but feel loose later?

Hats stretch with wear, especially leather sweatbands. The first fit should be snug because it will loosen by a quarter to half size over time.

How often should I measure my head?

Once. Adult head size does not change.

What if my head shape is unusual (long oval, narrow, etc.)?

Specialty hat brands sell long oval, round oval, and narrow profiles at the same numerical size. Your circumference measurement is the same. Match it to the shape variant for a better fit.

Do helmets use the same sizing as hats?

They use the same head measurement but with stricter tolerances. A loose helmet does not protect you. Use the head circumference number and the helmet manufacturer's specific chart — never size up a helmet.

Save the Number Once, Use It Forever

Your head circumference is a permanent number. Measure it once, write it down on your phone, never measure it again.

Head circumference (inches)
Head circumference (cm)

Two numbers. Every hat you buy online for the rest of your life lands on the right size on the first try. Stores running Tailor Size Guide embed sizing tools right on the product page so shoppers measure and order in one flow.

Selling hats, caps, or headwear on Shopify?

Sizing returns are the silent killer of margin in headwear. Tailor Size Guide adds size charts, custom measurement forms, and fit recommendations directly to your product pages so customers stop guessing and start ordering with confidence.

Install the Shopify app Read the docs