How to Measure Hat Size, and Convert It to Any System

Hat sizing is simpler than it looks, because it rests on a single measurement: the circumference of your head where the hat will sit. Everything else — US fractions, UK fractions, S-M-L — is just a different way of writing that number. Knowing how to measure hat size takes two minutes and a soft tape measure.

This guide shows where to measure, how to convert the number, and what to do if you land between sizes. More in our Size Guides section.

Measure around your head about one finger’s width above the ears and across the middle of the forehead. Your head circumference in centimetres is your European hat size.

What You Need

A soft, flexible tape measure
Or a piece of string and a ruler
A mirror, to check the tape is level
Your hair styled the way you usually wear it under a hat

How to Measure Your Head

Place the tape across the middle of your forehead, about a finger’s width above the eyebrows.
Take it around the sides of your head, about a finger’s width above the ears.
Bring it around the fullest part of the back of your head.
Keep it snug and level — touching all the way round but not pressing in.
Read the number where the tape meets, then measure again to confirm.

No tape measure? Wrap a piece of string around the same line, mark where it meets, then lay it flat against a ruler. The result is just as accurate if you keep the string level.

Converting Your Measurement

The European system is the simplest: your head circumference in centimetres is your hat size, so a 57 cm head wears a size 57. US hat sizes are based on the diameter in inches, and UK sizes run one-eighth smaller than US.

Head (cm)	Head (in)	European	US	UK	Letter
54	21¼	54	6¾	6⅝	XS
55	21⅝	55	6⅞	6¾	S
56	22	56	7	6⅞	S
57	22½	57	7⅛	7	M
58	22⅞	58	7¼	7⅛	M
59	23¼	59	7⅜	7¼	L
60	23⅝	60	7½	7⅜	L
61	24	61	7⅝	7½	XL
62	24⅜	62	7¾	7⅝	XL

Letter sizes vary between brands more than any other system. Use them as a rough guide, and check the brand’s own chart when a hat is sold in S, M and L.

The calculator converts your measurement into every system at once and gives the head-shape guidance that most charts leave out.

If You Are Between Sizes

Choose the larger size. A hat slightly too big can be made smaller with a sizing insert or hat tape inside the band; a hat too small is uncomfortable and leaves a red mark, and stretching it is harder. What to do between sizes covers the same rule for other garments.

Head Shape Matters Too

Heads are not perfectly round. Some are longer front to back; others are rounder. Two people with the same circumference can find the same hat fits one comfortably and presses at the front and back on the other. If a hat in your size presses at the forehead and the back but gaps at the sides, the shape is the issue, not the size — how a hat should fit explains what to look for.

For the styles themselves, see hat types and sizing and the best hats for your face shape, with the face shape detector if you do not know yours. To keep a good hat in shape, read how to store and care for a felt hat. The same measure-first approach works for gloves — try the glove size calculator.

Frequently Asked Questions

How do I measure my hat size?

Wrap a soft tape around your head about a finger’s width above the ears and across the middle of the forehead. The circumference is your size.

What is my European hat size?

Your head circumference in centimetres. A 57 cm head wears a European size 57.

What is the difference between US and UK hat sizes?

UK sizes run one-eighth smaller. A US 7⅛ is a UK 7.

Should I size up or down in hats?

Up. A slightly large hat can be adjusted with a sizing insert; a small one cannot easily be made bigger.

Can I measure my hat size without a tape measure?

Yes. Use a piece of string around the same line, mark where it meets, and measure the string against a ruler.

For background on how hat sizes are defined in different countries, see hat size, and for the traditional craft, hatmaking.

Hat Types and Sizing: How Each Style Should Be Sized

Not every hat is sized the same way. A felt fedora comes in exact sizes and has to fit precisely; a knit beanie stretches to fit almost anyone; a beret is often sold in a single size. Understanding hat types and sizing tells you how careful you need to be before ordering, and when a single measurement decides everything.

This guide covers ten common styles, how each is sized, and how much the size matters for each. More in our Size Guides section.

Structured hats in felt or straw need an exact size; knit and soft hats stretch and are far more forgiving. The more rigid the hat, the more the measurement matters.

The Four Ways Hats Are Sized

Sizing type	How it works	How precise it needs to be
Fitted	Sold in exact sizes by head circumference	Very — measure first
Adjustable	A strap, drawstring or inner band sets the size	A range, usually wide
Stretch	Knit or elastic fabric fits a range of heads	Forgiving
One size	A single size meant to fit most heads	Check the stated range

Ten Hat Types and How They Are Sized

Fedora

A soft felt hat with a pinched crown and a medium brim. Usually fitted, sold in exact sizes. Measure carefully, because a fedora that is too small sits on top of the head and one too large drops over the ears.

Trilby

Similar to a fedora but with a shorter, angled brim. Fitted sizing, same care as a fedora.

Panama

A lightweight woven straw hat, often in a fedora shape. Fitted sizing. Straw does not stretch, so the size must be right from the start.

Wide-Brim Sun Hat

Straw or felt with a broad brim. Often fitted, sometimes with an adjustable inner band. The size matters because a wide brim catches the wind.

Cloche

A close-fitting, bell-shaped hat worn low on the forehead. Fitted sizing, and a snug fit is part of the style.

Beret

A soft, flat, round wool hat. Often sold in one size, with some stretch at the band. Very forgiving.

Beanie

A close-fitting knit hat. Stretch sizing, usually one size. The most forgiving hat there is.

Bucket Hat

A soft fabric hat with a downward-sloping brim. Often sold in S-M-L or one size, sometimes with a drawstring.

Baseball Cap

A soft crown with a stiff peak. Usually adjustable at the back with a strap or snap, fitting a wide range.

Boater

A stiff straw hat with a flat crown and flat brim. Fitted sizing, and rigid, so precise.

How Much the Size Matters, by Style

Style	Sizing	Precision needed
Fedora, trilby	Fitted	High
Panama, boater	Fitted	High — straw does not stretch
Wide-brim sun hat	Fitted or adjustable	Medium to high
Cloche	Fitted	High
Bucket hat	S-M-L or one size	Medium
Baseball cap	Adjustable	Low
Beret	One size	Low
Beanie	Stretch	Very low

Straw hats do not stretch. A panama, boater or straw sun hat that is too small will stay too small, so measure carefully before ordering one.

For any fitted hat, measure first and convert the number into the system the brand uses.

Full instructions are in how to measure hat size; for what a good fit feels like once the hat arrives, read how a hat should fit.

Choosing a Style

The right style depends on your face shape and your wardrobe as much as the size. A fedora works with tailoring and a trench coat; a beanie with casual layers; a panama with summer linen. The best hats for your face shape covers proportion, with the face shape detector if you are unsure of yours.

For travel, a panama or straw sun hat is one of the most useful things to pack for a southern European summer — see what to pack for Italy in summer. For winter, a felt hat is one of the winter accessories worth investing in, and how to store and care for a felt hat keeps it in shape. The personal style quiz helps decide which styles feel like you.

Frequently Asked Questions

What are the main types of hat?

Fedora, trilby, panama, wide-brim sun hat, cloche, beret, beanie, bucket hat, baseball cap and boater are among the most common.

Which hats need an exact size?

Structured hats in felt or straw — fedoras, trilbies, panamas, cloches and boaters. Knit and soft hats are far more forgiving.

Do straw hats stretch?

No. A straw hat that is too small will stay too small, so measure carefully before ordering.

What does one size fits most mean for hats?

The hat has stretch or adjustment designed to fit a common range of head sizes. Check the stated range if your head is smaller or larger than average.

Are beanies sized?

Usually not. Most beanies are one size and rely on the stretch of the knit to fit.

For background on the styles, see list of hat styles and the panama hat.

How Should a Hat Fit? Five Signs It Is Right

A hat in the right size can still fit badly, and a hat that feels fine in the shop can give you a headache by lunchtime. Knowing how a hat should fit comes down to five signs, all of which you can check in a mirror in under a minute.

This guide covers where a hat should sit, the five signs of a good fit, and how to fix one that is slightly off. More in our Size Guides section.

A well-fitting hat sits level about a finger’s width above the ears and eyebrows, stays on in a light breeze, and leaves no red mark. You should be able to slide one finger between the band and your head.

Where a Hat Should Sit

Most structured hats sit level on the head, about a finger’s width above the eyebrows at the front and above the ears at the sides. The band rests on the widest part of the head, not on top of it.

Some styles sit differently by design: a cloche sits lower on the forehead, a beret sits further back or tilted, and a beanie can be worn high or low. For those, the position is part of the style rather than a sign of fit.

Five Signs a Hat Fits

One finger slides comfortably between the band and your head
It sits level, about a finger’s width above your ears and eyebrows
It stays on when you turn your head quickly or walk in a light breeze
It leaves no red mark or line on your forehead after twenty minutes
It does not wobble or shift when you nod

Signs the Size Is Wrong

Too Small

It sits on top of the head rather than around it
It leaves a red line or causes a headache
It pops up when you move

Too Big

It drops over the eyebrows or ears
It shifts or spins when you turn your head
It blows off in a light breeze

Head Shape: When the Size Is Right but the Fit Is Not

Heads vary in shape as well as size. A longer, more oval head can find that a hat in the right circumference presses at the front and back while gapping at the sides; a rounder head can find the opposite. If a hat in your size feels tight in two places and loose in two others, the shape is the issue rather than the size.

A milliner can shape a felt hat to your head, and some hats are made in different head shapes. The hat size calculator includes head-shape guidance for this reason.

Pressure at the forehead and the back of the head, with gaps at the sides, usually means a long oval head in a rounder hat. It is a shape mismatch, not the wrong size.

Fixing a Hat That Is Slightly Off

Slightly Too Big

Add hat tape or a foam sizing insert behind the inner band. It takes up a little space and is invisible when the hat is on. This is why, between two sizes, the larger is the safer choice.

Slightly Too Small

A felt hat can sometimes be stretched a little with a hat stretcher or by a milliner. Straw hats generally cannot. Knit hats stretch on their own.

When you are between two sizes, choose the larger and add a sizing insert. It is a quick, cheap fix, and far more comfortable than a hat that is slightly too tight.

If you have not measured yet, start with how to measure hat size. For how precise each style needs to be, see hat types and sizing; for choosing a style, the best hats for your face shape and the face shape detector. Keep a good hat in shape with how to store and care for a felt hat, and for the same between-sizes rule across other garments, what to do between sizes. Gloves follow similar logic — see how a glove should fit.

Frequently Asked Questions

How should a hat fit?

Level on the head, about a finger’s width above the ears and eyebrows, with room to slide one finger under the band. It should stay on in a light breeze and leave no red mark.

How tight should a hat be?

Snug but comfortable. One finger should fit between the band and your head.

What do I do if my hat is too big?

Add hat tape or a foam sizing insert behind the inner band.

Can a hat be stretched?

Felt hats sometimes can, a little, with a hat stretcher or by a milliner. Straw hats generally cannot.

Why does my hat hurt at the front and back?

Usually a head-shape mismatch — a longer oval head in a rounder hat — rather than the wrong size.

For background on how hat sizes are defined, see hat size, and on the craft of fitting and shaping hats, the hatmaker.