Hat size chart and calculator
Measure around your head once and get the fitted size, the letter size and the centimetre label.
Brands vary. These conversions follow New Era's 59FIFTY fitted size chart. Another label can run half a size (or a whole size) different, so if the store publishes its own chart, trust that first. All sources
A hat size is your head's diameter
Fitted sizes treat your head as a circle. Change your head measurement above and watch the diameter become the size.
Circumference: 22.64 in
÷ π (3.1416) = 7.206 in
≈ 7 1/4
Rounded to the nearest eighth of an inch, the step fitted caps are made in. Each eighth of a size adds about 1 cm of circumference (π × ⅛ in).
Fitted-cap sizes are really head diameters in eighths of an inch, a little geometry hiding on the label; ahaboo applies that kind of unhurried geometry to the sky, showing why the Moon appears to change shape.
Hat size chart
| Fitted | Head (cm) | Head (in) | Letter |
|---|---|---|---|
| 6 7/8 | 54.9 | 21 5/8 | S |
| 7 | 55.8 | 22 | M |
| 7 1/8 | 56.8 | 22 3/8 | M |
| 7 1/4 | 57.7 | 22 3/4 | L |
| 7 3/8 | 58.7 | 23 1/8 | L |
| 7 1/2 | 59.6 | 23 1/2 | XL |
| 7 5/8 | 60.6 | 23 7/8 | XL |
| 7 3/4 | 61.5 | 24 1/4 | XXL |
| 7 7/8 | 62.5 | 24 5/8 | XXL |
| 8 | 63.5 | 25 | XXL |
| 8 1/8 | 64.5 | 25 3/8 | XXXL |
| 8 1/4 | 65.4 | 25 3/4 | XXXL |
Questions shoppers ask
What is 7 1/4 hat size in cm?
A 7 1/4 fitted hat is about 57.7 cm (22 3/4 in) head circumference on New Era's 59FIFTY chart.
How do I measure my head for a hat?
Wrap a soft tape around your head where the hat sits: about 1 cm (half an inch) above the eyebrows and ears, around the widest part at the back. Keep it level and snug but not tight.
Where do fitted hat sizes like 7 3/8 come from?
They are the diameter of the head in inches. Divide your head circumference in inches by pi (3.14) and round to the nearest eighth: a 23-inch head gives 7.32, sold as 7 3/8.
Should I size up if I am between hat sizes?
Yes. New Era's retailers advise buying the larger size, since wool fitted caps can shrink and a tight hat gets less comfortable over the day.