Hat size calculator
| Head circumference | US hat size | Letter size |
|---|---|---|
| up to 20 in (51 cm) | 6 3/8 | XXS |
| 20 1/8–20 3/8 in (51.1–52 cm) | 6 1/2 | XS |
| 20 1/2–20 3/4 in (52.1–53 cm) | 6 5/8 | XS |
| 20 7/8–21 1/4 in (53.1–54 cm) | 6 3/4 | S |
| 21 3/8–21 5/8 in (54.1–55 cm) | 6 7/8 | S |
| 21 3/4–22 in (55.1–56 cm) | 7 | M |
| 22 1/8–22 3/8 in (56.1–57 cm) | 7 1/8 | M |
| 22 1/2–22 3/4 in (57.1–58 cm) | 7 1/4 | L |
| 22 7/8–23 1/8 in (58.1–59 cm) | 7 3/8 | L |
| 23 1/4–23 1/2 in (59.1–60 cm) | 7 1/2 | XL |
| 23 5/8–24 in (60.1–61 cm) | 7 5/8 | XL |
| 24 1/8–24 3/8 in (61.1–62 cm) | 7 3/4 | XXL |
| 24 1/2–24 3/4 in (62.1–63 cm) | 7 7/8 | XXL |
| 24 7/8–25 1/8 in (63.1–64 cm) | 8 | XXXL |
| 25 1/4–25 1/2 in (64.1–65 cm) | 8 1/8 | XXXL |
| 25 5/8–25 7/8 in (65.1–66 cm) | 8 1/4 | 4XL |
| 26 in (66.1 cm) and over | 8 3/8 | 4XL |
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Step 1 / 3
Take a front selfie
Look straight into the camera with your whole head in the frame, hair as you usually wear it, no hat. Even lighting works best.
Step 2 / 3 · optional
Now a side photo (~45°)
Turn your head slightly to one side for a second photo. The extra angle lets the AI fit the hat to the real shape of your head.
Step 3 / 3
Choose a hat
Pick a style from the gallery, or upload a photo of any hat you want to try.
- Measuring your face shape…
- Reading your proportions and hair…
- Matching hats to your face…
- Picking your best fit…
Analysis complete
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Hat sizes are your head circumference in disguise. A US fitted size like 7 3/8 is the circumference in inches divided by pi, rounded to the eighth; letter sizes from S to XXL each cover two of those eighths. So 23 inches around makes you a 7 3/8, or a large — and if you fall between two sizes, take the larger one: a band that is too tight gives you a headache within the hour, one a little loose can be fixed with sizing tape.
Measure where the hat will actually sit: a level line about a finger above your ears and across the middle of your forehead, with your hair the way you will wear it under the hat. Measure twice; if the readings differ, use the larger one. Fitted caps and felt hats follow the chart closely, while beanies and adjustable baseball caps forgive half a size either way.
Your head size also decides which hats look right on you, not just which ones fit. Wide brims and tall crowns swamp a small head, while a big head makes a small trilby look perched. Measure here, then take a selfie below: the AI reads your face shape and your proportions together with your head size.
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Measure your head
Run a soft tape measure around your head just above the ears and eyebrows, level all the way round.
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Enter the number
Type it in inches or centimeters; fractions like 22.5 work too.
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Read your size
You get your US fitted size and your letter size. Between two sizes, go one up.
FAQ
What hat size is 23 inches?
A head of 23 inches (58.4 cm) is a US 7 3/8, which most makers sell as a large (L). It falls between 7 1/4 (22 3/4 inches) and 7 3/8 (23 1/8 inches), and between two sizes you take the larger.
How do I know my hat size without a tape measure?
Wrap a piece of string or a phone charger cable around your head where a hat sits, mark the point where it meets, then lay it flat along a ruler or a tape from a toolbox. Enter that length here.
What is the average hat size?
Most adult men measure about 22 1/2 to 23 inches (57 to 58 cm), a US 7 1/8 to 7 1/4 (M to L); most women about 21 1/2 to 22 inches (55 to 56 cm), a 6 7/8 to 7 (S to M). From about 23 1/2 inches (60 cm, a 7 1/2 or XL) a head counts as big for off-the-shelf hats.
Are UK and European hat sizes the same?
European sizes are simply the circumference in centimeters, so a 58 is a 58 cm head. UK fitted sizes run one eighth below US ones: a US 7 3/8 is a UK 7 1/4.