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.
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.
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 |
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.
Hat Size Calculator
Head circumference to fitted, S/M/L and EU hat sizes.
Try this free calculator to find your exact match.
Frequently Asked Questions
How do I measure my hat size?
What is my European hat size?
What is the difference between US and UK hat sizes?
Should I size up or down in hats?
Can I measure my hat size without a tape measure?
For background on how hat sizes are defined in different countries, see hat size, and for the traditional craft, hatmaking.
Brand and sizing data on this site is reviewed quarterly. If a figure here is wrong, email fashion@womensfashioneu.com and it will be checked and corrected.
