What is hat size 7 in cm?

US hat size 7 corresponds to a head circumference of approximately 55.9 cm (22 inches). Hat sizes in the US are traditionally expressed as fractions of inches representing the hat's inner diameter (circumference ÷ π). Size 7 = 7 × π inches = 21.99 inches ≈ 56 cm circumference.

How do I measure my head for a hat?

Wrap a flexible tape measure around your head approximately 1 inch (2.5 cm) above your ears, across the middle of your forehead, and around the widest part at the back of your head. Keep the tape snug but not tight. This measurement in centimeters or inches is your head circumference, which you then look up in a hat size chart. If between sizes, choose the larger size.

What is a medium hat size in cm?

A medium (M) hat typically fits head circumferences of 57–58 cm (22.5–22.8 inches), corresponding to US hat sizes 7⅛ to 7¼. Large (L) typically covers 59–60 cm. However, size labeling varies by brand, so always check the specific brand's size chart when possible.

Hat Size Guide: Head Circumference to US, UK & EU Hat Sizes

Hat Size Conversion Chart

US hat sizes are traditionally expressed as fractions representing the inner diameter of the hat in inches (e.g. 7 means a 7-inch inner diameter, which fits a head with a circumference of approximately 7 × π ≈ 22 inches). UK sizes use the same inch-based fractions. EU sizes use the head circumference directly in centimeters.

Head Circumference (cm)	Head Circumference (inches)	US Size	UK Size	EU Size	Letter Size
52	20½	6½	6½	52	XS
53	20&frac78;	6&frac58;	6&frac58;	53	XS
54	21¼	6¾	6¾	54	S
55	21&frac58;	6&frac78;	6&frac78;	55	S
56	22	7	7	56	M
57	22½	7&frac18;	7&frac18;	57	M
58	22&frac78;	7¼	7¼	58	M
59	23¼	7&frac38;	7&frac38;	59	L
60	23&frac58;	7½	7½	60	L
61	24	7&frac58;	7&frac58;	61	XL
62	24&frac38;	7¾	7¾	62	XL
63	24¾	7&frac78;	7&frac78;	63	XXL
64	25¼	8	8	64	XXL

How to Measure Your Head for a Hat

Use a flexible fabric or paper tape measure (or a piece of string you can measure afterward with a ruler).
Position the tape about 1 inch (2.5 cm) above your ears, across the center of your forehead, and around the widest part of the back of your head.
Keep the tape snug — it should sit flat against your head without compressing your hair.
Note the measurement in centimeters. This is your head circumference and your EU hat size.
Divide your circumference in centimeters by π (3.14159) to get the US size in inches, then look up the nearest fraction.

Letter to Numeric Size Quick Reference

Letter Size	EU Size Range (cm)	US Size Range
XS	52–53	6½–6&frac58;
S	54–55	6¾–6&frac78;
M	56–58	7–7¼
L	59–60	7&frac38;–7½
XL	61–62	7&frac58;–7¾
XXL	63–64	7&frac78;–8

Tips for the Best Fit

If your measurement falls between two sizes, choose the larger size — a slightly large hat can be adjusted with hat tape, but a small hat cannot be stretched.
Fitted caps (baseball caps, fedoras) require an exact size. Snapback and adjustable hats fit a range of head sizes.
Hair volume matters: if you wear your hair up or have very thick hair, measure with your hair in its most common worn style.

Use our length converter to switch between centimeters and inches when comparing your measurements to hat charts from different countries.