Cap vs Hat Sizing

How cap sizing works

Most caps are sold in letter sizes, such as S, M, L and XL, or in one size with an adjustable strap at the back. A letter size covers a range of heads, so a cap in M will fit several head circumferences, and the strap takes up the slack for heads at the small end of the range. That makes cap sizing forgiving, and it is why a cap is often an easy first buy online.

A fitted cap with no strap is the exception, and it is sold by fitted US number like a hat. Check the product page before you assume a cap adjusts, because a fitted cap needs the same care as a fedora. Crown depth matters for caps too, because a shallow crown will perch on a tall head even when the band fits.

How hat sizing works

Most hats are sold by fitted US number, such as 7, 7 1/4 or 7 1/2, and each number is made for one head circumference. A hat in 7 1/4 is made for a head of about 58 cm, and a head of 59 cm will find it tight. That precision is why hats feel better when the size is right, and why they feel wrong when it is not, because there is no strap to take up the difference.

Some hats are sold in letter sizes too, but the letter is a rough guide over the fitted numbers inside it. A hat in letter L covers fitted 7 3/8 and 7 1/2, so two heads a full cm apart can wear the same letter. When both are printed, trust the fitted number and the cm figure over the letter.

Converting between cap and hat sizes

Conversion starts from the head circumference, not from a cap size you remember. Measure your head in cm, find the row in the hat size chart, and read the fitted number and the letter size for that row. That letter is the cap size to look for first, and the fitted number is the hat size to look for first, and both come from the same measurement.

A cap in M usually covers heads from about 57 cm to 59 cm, which is fitted 7 1/8 to 7 3/8, so a head at either end of that range will find the same cap fits differently. A fitted hat in 7 1/4 covers only heads near 58 cm, so the same head will feel more precise in the hat. Use the hat size conversion chart to read across between the systems.

Fit differences between caps and hats

A cap fits with a curved brim at the front and a band that sits just above the eyebrows and ears, and the adjustable strap lets you tighten it through the day. A hat fits with a brim all the way around and a firm band that must grip evenly on its own, because there is no strap to help. That makes a hat more sensitive to head shape, while a cap is more sensitive to crown depth.

A cap that is slightly large can be tightened, while a hat that is slightly large needs sizing tape. A cap that is slightly small can be loosened at the strap, while a hat that is slightly small will press all day. The cap forgives, and the hat demands, which is why a careful measurement matters more for a hat than for a cap.

Choosing between a cap and a hat

Choose a cap when you want an easy fit, sun shade at the front, and a size you can adjust. Choose a hat when you want shade all round, a structured look, and a fit that stays put without a strap. A first time buyer who is unsure of their size is safer with an adjustable cap, while a buyer who knows their fitted size will get a better fit from a hat.

If you wear both, keep one measurement for both, but use it differently. The cap size is the letter for your row, and the hat size is the fitted number for your row. Our hat styles and their fit guide compares the cap with the other four common styles, so you can see where each one fits best.