How do I measure my head for a hat?

Wrap a soft measuring tape around your head about 1 cm above your ears and eyebrows, where the hat band will sit. Hold the tape snugly but not tightly. Measure in cm or inches and match to the EU or US column in the chart.

What does a US hat size like 7¼ mean?

US hat sizes are based on head circumference in inches divided by π (≈ 3.14159). A size 7¼ corresponds to a 7.25 × π ≈ 22.78 inch (≈ 57.9 cm) head circumference — roughly the internal circumference of the hat.

Is a Large hat the same size everywhere?

No — S/M/L/XL labels vary significantly by brand and country. Always check the cm or inch measurement for the most consistent sizing. An L in one brand may be equivalent to XL in another.

Are UK and US hat sizes the same?

Yes — UK and US hat sizes use the same fractional system and are interchangeable. Both are based on head circumference ÷ π expressed in inches.

How do fitted baseball caps use hat sizes?

Fitted baseball caps (like New Era 59FIFTY) use the same US hat sizing system. Size 7 = 55.8 cm head circumference; 7½ = 59.7 cm. Flex-fit hats use S/M or L/XL bands that stretch to fit a range of circumferences.

Hat Size Converter — US, UK, EU, cm Head Circumference

Hat Size Converter

Hat sizes are based on head circumference — the measurement around the largest part of your skull, about 1 cm above your eyebrows. In the US, hat sizes are expressed as fractions of inches (6⅝, 7, 7⅛); in Europe they are the head circumference in centimeters; in the UK they use the same fractional inch scale as the US.

How it works

US hat size = head circumference (inches) / π
EU hat size = head circumference (cm)

US to EU:  EU = US × π × 2.54
EU to US:  US = EU / (π × 2.54)

Example: US 7¼ = 7.25 in × π × 2.54 = 57.9 cm ≈ EU 58

The US system originated in the 19th century when hatmakers measured the interior circumference of a finished hat and divided by π to get a simple number corresponding to the hat's inner diameter in inches.

Practical examples

Example 1 — Measuring your head. Wrap a flexible tape measure around your head 1 cm above your eyebrows (the widest point of your skull). Keep the tape snug but not tight. Example measurement: 58 cm → EU 58 → US 7¼.

Example 2 — Converting a European size for a US store. Hat is EU 56. US equivalent: 56 / (π × 2.54) = 56 / 7.9796 = 7.02 → rounds to US 7.

Example 3 — Fitted baseball cap. US caps are labelled 6⅞ to 8. If your head measures 55 cm: 55 / 7.9796 = 6.89 → size 6⅞.

Common mistakes

Measuring too high or too low. The tape should sit 1 cm above your eyebrows and across the widest part of the back of your skull. Higher readings produce a smaller number (the head narrows toward the crown); lower readings produce a larger number.
Measuring over thick hair. Fine hair adds little; coarse or thick hair can add 1–2 cm. Style your hair as you normally would when wearing hats.
Confusing "one size fits most" with actual fit. One-size caps use an adjustable strap and typically fit head circumferences of 55–62 cm (US 6⅞–7¾). Heads outside that range — especially larger — will not fit comfortably.
Ignoring hat type and material. Wool felt stretches slightly with wear; woven straw does not. Knit beanies are elastic and sized by small/medium/large rather than circumference.

International and regional variations

Size label	US / UK fraction	EU (cm circ.)	Head circumference range (cm)
XS	6⅜–6½	51–52	51–52
S	6⅝–6¾	53–54	53–54
M	6⅞–7	55–56	55–56
L	7⅛–7¼	57–58	57–58
XL	7⅜–7½	59–60	59–60
XXL	7⅝–7¾	61–62	61–62
XXXL	7⅞–8	63–64	63–64

Quick reference

Head circ. (cm)	EU size	US / UK size	Label
51	51	6⅜	XS
52	52	6½	XS
53	53	6⅝	S
54	54	6¾	S
55	55	6⅞	M
56	56	7	M
57	57	7⅛	L
58	58	7¼	L
59	59	7⅜	XL
60	60	7½	XL
61	61	7⅝	XXL
62	62	7¾	XXL

Click a row to highlight it. Measure head circumference at the widest point, about 1 cm above the ears.

Label	US	UK	EU	Head circ. (cm)
XS	6⅜	6⅜	51	51–52
S	6⅝–6¾	6⅝–6¾	54	53–55
M	6⅞–7	6⅞–7	56	56–57
L	7⅛–7¼	7⅛–7¼	58	58–59
XL	7⅜–7½	7⅜–7½	60	60–61
2XL	7⅝–7¾	7⅝–7¾	62	62–63
3XL	7⅞–8	7⅞–8	64	64–65

Frequently Asked Questions

How do I measure my head for a hat?: Wrap a soft measuring tape around your head about 1 cm above your ears and eyebrows, where the hat band will sit. Hold the tape snugly but not tightly. Measure in cm or inches and match to the EU or US column in the chart.
What does a US hat size like 7¼ mean?: US hat sizes are based on head circumference in inches divided by π (≈ 3.14159). A size 7¼ corresponds to a 7.25 × π ≈ 22.78 inch (≈ 57.9 cm) head circumference — roughly the internal circumference of the hat.
Is a Large hat the same size everywhere?: No — S/M/L/XL labels vary significantly by brand and country. Always check the cm or inch measurement for the most consistent sizing. An L in one brand may be equivalent to XL in another.
Are UK and US hat sizes the same?: Yes — UK and US hat sizes use the same fractional system and are interchangeable. Both are based on head circumference ÷ π expressed in inches.
How do fitted baseball caps use hat sizes?: Fitted baseball caps (like New Era 59FIFTY) use the same US hat sizing system. Size 7 = 55.8 cm head circumference; 7½ = 59.7 cm. Flex-fit hats use S/M or L/XL bands that stretch to fit a range of circumferences.