How to measure a hat
Every point, drawn on the garment so there is no guessing where the tape goes.
Quick answer
Measure a hat at three points: circumference, height and rim, in that order of fit-impact. Circumference is the sizing number, taken right around the inside of the sweatband, the inner opening most guides never name. Hover or tap each step on the diagram to see exactly where the tape sits. Sizely turns those numbers into a size chart buyers trust.
A buyer checks one thing first on a hat: will it sit on my head. That answer is the circumference, the inner band opening, and it is the number sizing runs on. Generic listings give a vague S/M/L and stop. This page draws all three points on the actual hat, so the head opening, the crown depth and the brim all get a real measurement.
- A
Circumference
The number that decides whether the hat fits, so it leads. Run the tape around the inside of the sweatband where it meets the head, following the full inner opening. Hover or tap this step to see the loop the tape traces. This is the head size buyers match against their own measurement.Taken around the inner opening, so it already reads the full head circumference. Do not double.
- B
Height
How tall the crown stands, measured straight up from the band to the top of the hat. Tap the step to see where the line starts and ends. A taller crown sits high and roomy, a shorter one hugs close to the head.Recorded as-is. Do not double.
- C
Rim
The brim width, taken straight out from the base of the crown to the outer edge of the rim. This sets the look and how much shade the hat throws.Recorded as-is. Do not double.
Measure flat and relaxed, never stretched. Lay the sweatband in a smooth circle and read it without pulling, since a knit or fitted band can stretch an inch and throw the size off. Circumference is taken around the inner opening, so the tape already reads the full head size as-is. Height and rim are single straight runs, also recorded exactly as measured. Nothing on a hat doubles.
Hat size reference
| Size | Circumference | Height | Rim |
|---|---|---|---|
| S | 21.5 | 4 | 2.25 |
| M | 22.5 | 4.25 | 2.5 |
| L | 23.5 | 4.5 | 2.5 |
| XL | 24.5 | 4.75 | 2.75 |
| 2XL | 25.5 | 5 | 2.75 |
Frequently asked
How do I measure my head for a hat?
Wrap a soft tape around the widest part of your head, about a finger-width above your ears and eyebrows, where the band would sit. Keep the tape level and snug but not tight. That number is your head circumference, and it should match the hat's inner band measurement. For the full sizing run with US, UK and EU equivalents, see our hat size chart.
Do I double the hat circumference measurement?
No. The hat circumference is taken all the way around the inner opening, so it is already the full head size. This is different from a flat chest or waist measurement, where the tape only crosses one folded layer and you double it. A hat's band is a closed loop, so the number you read is the number a buyer wears.
What hat size am I from my head measurement?
Match your head circumference in inches to the hat's inner band number. As a rough guide, about 22 inches is a Small to Medium, 23 inches a Large, and 24 inches an XL, though brands vary. For exact US fitted sizes and international conversions, check our hat size chart rather than guessing from a generic S/M/L label.
Should I measure a hat in inches or centimeters?
Either works, as long as you label the unit and stay consistent. Hat sizing is one of the most international categories, so listing both inches and centimeters helps buyers who think in different systems. Sizely shows both on every chart, so no buyer has to convert in their head.
Why does the same hat size feel different between brands?
Because the band stretch, lining thickness and shape vary, two hats labeled the same can sit differently. A stiff fitted cap reads true to its band number, while a knit or adjustable hat gives. Listing the real inner circumference, not just S/M/L, is the most reliable way to set a buyer's expectation.
Related size charts & tools
Hat size chart
How to measure a capSources: Sizely garment engine, spec #28 (Hat), three named measurement points. EN 13402 body-dimension sizing reference (head girth, representative ranges only). Last verified June 2026.
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