Measure your head circumference about half an inch above the eyebrows, keep the tape level and snug, and match the number to the cap maker’s own chart.
There is no universal “small fit.” A 21¾-inch head lands in one brand’s small and a few millimeters from another’s medium, so measure before buying. Here is the method, the sizing ranges worth knowing, and the mistakes that produce a cap you’ll never wear twice.
How Do You Measure Head Circumference for a Cap?
Measure around the head where the sweatband sits: roughly ½ inch above the eyebrows, just above the ears, level across the widest part of the back of the skull. A flexible sewing tape works best; string or a shoelace measured against a ruler works too.
- Center the tape on the forehead about ½ inch above the eyebrows.
- Wrap it around the sides just above the ears, then across the back of the skull.
- Keep the tape level and untwisted. A sloping tape gives a short, wrong number.
- Pull it snug, not tight. Excess tension produces a cap that turns out too small.
- Write down the measurement in inches or centimeters; centimeters are more precise.
- Measure again and trust only a number you get twice.
- Compare it to the cap maker’s chart for that specific model.
The tape should contact the head everywhere without leaving a dent. If it marks your forehead, it’s too tight.
What Head Measurement Counts as a Small-Fit Cap?
Small labels cluster around 21–22 inches, but boundaries belong to each manufacturer. One published chart runs:
| Label | Head Circumference | Hat Size |
|---|---|---|
| XS | 20–20⅞ in / 52–53 cm | 52–53 |
| SM | 21–21⅞ in / 54–55 cm | 54–55 |
| MD | 22–22¾ in / 56–57 cm | 56–57 |
New Era’s fitted 59FIFTY line opens at size 6⅞ (21⅝ in / 54.9 cm), steps to 7 at 22 inches, then 7⅛ at 22⅜ inches, and runs through size 8 (25 in / 63.5 cm). Between two fitted sizes, New Era advises rounding up.
Adjustable caps differ: New Era lists its 9FIFTY S/M sizing at 21⅝, 22, and 22⅜ inches depending on model, and the same product may be tagged One Size, S/M, or M/L—a range, not a fitted size.
What Are the Most Common Measuring Mistakes?
- Measuring across the top of the head instead of its widest practical circumference.
- Setting the tape too high or too low relative to the sweatband.
- Pulling tight (understates size); holding loose (overstates it).
- Letting the tape slope or twist, producing a low reading.
- Measuring once and skipping confirmation.
- Converting inches to centimeters by eyeball instead of reading the chart.
- Borrowing another brand’s chart without checking fit.
- Treating an adjustable range as a fitted size.
Even a correct circumference doesn’t guarantee comfort: crown shape, material, sweatband thickness, hairstyle, and wear position all matter. Our roundup of hats sized for smaller head shapes narrows the search by how each one sits.
How Do You Use the Measurement to Choose a Cap?
Match your circumference to the chart for that exact cap model, not the brand’s general sizing page. Note the number in both inches and centimeters, and keep fit notes on your phone. New Era’s sizing chart lists every fitted size from 6⅞ to 8, making each order a two-minute job.
A safety note that doubles as a fit check: a hat that creates pressure, brings on a headache, causes numbness, or interferes with vision is the wrong size. Loosen it, resize it, or replace it.
In short: measure twice at sweatband height, match the specific model’s chart, round up between New Era fitted sizes, and recheck fit when the cap arrives.
Common Questions
Can I measure my head with a piece of string?
Yes. Wrap string at the same height and tension as a tape, mark the meeting point, and lay it flat against a ruler. Repeat until two readings match—string stretches, so one reading can drift.
Should I size up if I’m between two fitted sizes?
New Era recommends rounding up. Fitted caps have no closure to give; a slightly roomy cap can be adjusted with a sweatband or worn lower, while a too-tight one has nowhere to go.
Does a small-fit cap fit the same in every brand?
No. “Small,” “S/M,” and “small fit” share no measurements, and each maker draws its own ranges. Two caps labeled the same size from different companies can differ by an inch in actual circumference.
My measurement matches the chart but the cap still feels tight — why?
Crown depth, sweatband thickness, and material stiffness all matter beyond circumference. A shallow crown on a deeper head, or stiff unstructured panels, can press even when the tape was right. If it causes pressure or headache, size up or pick a different construction.
Sources
- New Era Cap. “Sizing Chart” Supplies the 59FIFTY fitted-size and 9FIFTY S/M measurements and the rounding-up guidance.