Wool Flat Cap Sizing Guide: How to Measure Your Head

Measure an inch above the eyebrows and just above the ears with a soft tape, then match that number to the cap maker’s own chart — most men land between 22 and 23 inches.

For the full breakdown, see our best Wool Flat Cap guide.

A wool flat cap that pinches or slides down is rarely a bad cap — it’s a bad measurement, usually taken around the crown instead of the wearing line. Get that loop right and sizing falls into place.

Flat caps are trickier than baseball caps because wool has little give and labels (XS–XXL, or US sizes like 7 1/4) aren’t standardized. The tape is half the job; reading the specific chart is the other half.

How to measure your head for a wool flat cap

Run a soft tailor’s tape horizontally around your head at the wearing line — about 1 inch above the eyebrows, just above the ears, level around the back of the skull. Snug without pressing in.

1. Find the line. Roughly 1 inch above the eyebrows and just above the ears; some makers use mid-forehead, so check their instructions.
2. Wrap and level. Around the widest practical circumference, including the back of your head, flat all the way around — not tilted up at the back.
3. Snug, not tight. Contact, not compression — too tight feels restrictive, too loose slips.
4. Read it in centimeters. Smaller units give more precision against a chart.
5. Repeat two or three times. Use the consistent number. A second pair of hands helps.

No tape? Use a non-stretch string or ribbon, mark it, and lay it against a ruler. Skip elastic — it stretches and throws the number off.

Once you have the circumference, check the chart for that exact cap. A tested wool flat cap roundup is worth a look before committing, since fit notes flag whether a model runs snug or roomy. The measurement is the input; the maker’s chart is the translator.

Reading the size charts: US hat sizes vs. cap labels

Letters and US hat sizes don’t line up the same way across brands — treat general conversions as a starting point and the product’s own chart as final. The US scale runs from 6 3/8 (about 20 1/4 inches, or 51 cm) to 8 (about 25 1/2 inches, or 64 cm); cap charts map these to letters, sometimes as ranges.

The gaps between ranges are deliberate for wool. Charts also disagree at the margins: one list calls size 7 about 21 7/8 inches, another 22 1/4. Same label, different number — which is why you check the seller’s chart. Stetson publishes its own guidance, a good example of manufacturer charts overriding generic tables.

If you’re between sizes or unsure about fit

Round up. A slightly roomy wool flat cap can be nudged into place or gently shrunk; one that’s too small has nowhere to go.

Circumference alone doesn’t guarantee comfort — crown shape, lining, and wool structure all change how a cap feels, and two caps in the same labeled size from different makers can sit completely differently.

Common measurement mistakes:

• Measuring around the crown instead of the wearing line
• Pulling the tape too tight or letting it sag
• Using elastic or stretchy material as a stand-in tape
• Taking a single measurement and calling it done
• Converting inches to centimeters to hat size without checking the product chart

The manufacturer’s model-specific guidance always wins — if their page says a cap runs large, trust it. Stetson’s hat size guide lays out its own method and chart, useful when comparing an unfamiliar brand.

Final check: tape at the correct line → snug → centimeters recorded → measured twice → compared against that cap’s chart → rounded up if between sizes.