Hat Size Converter

US fitted hat sizes (6 3/4, 7, 7 1/4…) are based on head circumference — the number roughly equals head diameter in inches multiplied by π, though labels use fractional inch steps. Measuring your head in centimeters is the most reliable way to match a cap chart.

Wrap a soft tape around the forehead where the hat sits — about 1 cm above the ears. Snug but not tight. Compare your cm measurement to the brand chart; fitted, adjustable, and stretch caps fit differently.

Example: 58 cm head ≈ US 7 1/4 fitted hat ≈ 22.75 in circumference. Between sizes? Size up for beanies, down for structured caps — or choose adjustable styles.

US fitted hat sizes are fractional inches that correspond to head circumference divided by π, rounded to common steps (6¾, 7, 7¼…). Measuring circumference in centimetres with a soft tape is more reliable than guessing from an old cap's label.

Measure around the forehead about 1 cm above the ears and across the fullest part of the back of the head — snug but not tight, with hair as you normally wear it under a hat. That is the figure European brands list directly as cm size.

Between sizes, size up for structured fitted caps (they do not stretch) and consider sizing down or choosing stretch for beanies. Adjustable snapbacks and strapbacks span a range and do not need a precise fitted fraction.

Cycling, ski, and climbing helmets almost always use cm circumference on the label — the same measurement as fitted hat charts — so one tape reading serves both.

Children's charts are usually cm-only. Adult US fitted fractions do not map cleanly onto toddler sizes; measure and use the brand's age-or-cm table rather than converting from an adult size.

Structured caps fit tighter than beanies at the same circumference — round up when between fitted sizes.

Cycling and ski helmets use cm head circumference on the label — same measurement as fitted hat charts.

One-size caps with snapbacks span a range — fitted size charts apply to structured caps without adjusters.

Children's hat charts use cm circumference exclusively on many EU labels — convert adult fitted sizes the same way.