How to Measure Your Head for a Sun Hat | Sizing That Holds

A flexible tape run about one inch above the eyebrows and just over the ears gives your hat size — snug, level, and read in both centimeters and inches.

A sun hat that slides over your eyes or blows off in a gust is almost always a measuring mistake. Getting the number right takes about two minutes with a tailor’s tape. The steps below cover the measurement, US size conversions, and fit checks a circumference alone won’t catch, ending with sun-protection specs worth shopping for.

How Do You Measure Head Circumference Correctly?

Wrap a flexible, non-stretch tailor’s tape around your head where the hat will sit, keep it horizontal, and record the overlap point.

• The line: roughly 1 inch above the eyebrows and immediately above the ears. Measuring higher gives a smaller number than the hat needs.
• The tape: a cloth tailor’s tape is ideal. No tape? Use non-stretch string or ribbon, mark the overlap, then measure it flat against a ruler. Elastic or stretchy cord skews the result.
• The tension: snug against the skin without pressing in or flattening your hair.
• The level: keep the tape even all the way around. Angling it down at the back is the most common error and shrinks the measurement.
• The repeat: measure two or three times and use the recurring number.

Measure with your hair the way you normally wear it under a hat. Thick hair can push you up a size for comfort, though published guides don’t set a standard allowance for it.

What US Hat Size Is Your Measurement?

Match your centimeter reading to the manufacturer’s own chart first, then fall back to a published conversion table. The University of Bristol’s graduation guide and Alfred University’s safety office both publish numeric US conversions in the same range. The Alfred chart also gives the rule that resolves most ordering dilemmas: when your measurement lands between two sizes, take the larger one — a slightly big hat can be tightened with a sweatband or chin cord; a small one presses on your forehead all afternoon.

Treat that table as a bridge, not a guarantee. Conversions shift between manufacturers, and some brands skip numeric sizing — Arc’teryx, for instance, sizes hats in product ranges (S–M at 55–57 cm, L–XL at 58–60 cm, one size fits all at 55–60 cm). Alfred University’s hat sizing guide is a solid reference for the numeric scale, but the product page always wins. For the upper end of that table, our roundup of XXL sun hats for big heads covers models built around larger circumferences and adjustable fits.

Why Head Circumference Alone Doesn’t Guarantee Comfort

A correct number gets you the right size range; the hat still has to sit well on your head shape. Check three pressure points: the forehead, temples, and just above the ears. Any spot that throbs or leaves a red line within minutes means too tight, whatever the label says. A loose hat slides when you tilt your head or catch a breeze. Look for an adjustable sweatband, chin cord, or rear drawstring — those buy back a half size either way. Check the adjustment range, brim width, and fit notes before ordering.

Mistakes to avoid: measuring above your wearing line, pulling the tape tight, using stretchy string, measuring once, confusing head circumference with brim circumference (unrelated numbers), and relying on a generic S/M/L chart when the manufacturer publishes a model-specific one.

What Sun Protection Should the Hat Actually Provide?

Look for a brim of at least 3 inches — enough to shade the face, ears, and back of the neck. A baseball cap leaves the ears and neck exposed.

Fabric rating matters too. UPF 50 blocks about 98% of solar radiation and lets roughly 2% through — though that applies to the fabric, not to seams or uncovered skin. UV also bounces off water, sand, and pavement, so pair the hat with shade, sunglasses, and broad-spectrum water-resistant sunscreen of SPF 30 or higher. Confirm models, prices, and specs on the exact product page.