Shirt Collar Size: What 15.5 Inches Actually Measures

A 15.5 inch collar is not 15.5 inches of neck. It is the inside circumference of a buttoned collar, measured around the band, and it already includes about 1.5 cm of ease. Your neck is the smaller number, and the gap is the shirt.

Measure the neck, not the old collar

Run the tape around the base of the neck, at the point where the collar band sits, not at the widest part. Keep one finger under the tape. Do not add a second finger for “comfort”: shirt makers build 1.2 to 1.5 cm of ease into the finished collar, and a second finger often doubles it.

Measure in the afternoon if you can. Necks swell slightly through the day, and a collar that fits at 8 a.m. can press at 6 p.m.

Inch sizes and centimetre sizes do not quite line up

Collar (in)	Collar (cm)	Typical neck
14.5	37	36 cm
15	38	37 cm
15.5	39.5	38 cm
16	41	39.5 cm
16.5	42	40.5 cm
17	43	41.5 cm

Half-inch steps are 1.27 cm, while European sizes move in whole centimetres, so a 16 inch collar lands between 40 and 41 on most conversion charts. When both are printed, use the centimetre number on the tag and ignore the converted inch figure.

Collar point length changes the look, not the fit

Point length runs from the collar band seam to the tip. Dress shirts usually sit between 7 and 9 cm. A point under 7 cm reads casual and works without a tie; past 9 cm the points spread wide and demand a wide knot.

The spread is the distance between the two points when the collar is buttoned, usually 8 to 11 cm. A narrow spread of 7 cm makes a small knot look larger. None of this changes the neck size, which is why a shirt can fit at the collar and still look wrong.

Shrinkage is the number nobody budgets

Cotton shrinks along the warp more than the weft. An untreated poplin collar can lose 1 to 2 percent in the first few washes, which is 4 to 8 mm on a 39 cm collar. That is the difference between a collar that closes with a finger of room and one that does not.

Pre-shrunk and sanforized cotton lose under 1 percent. The label will say so if the fabric was treated. If it does not, buy the half size up, especially in oxford cloth, which is woven loosely and moves more than poplin.

The collar band is a separate measurement

Band height is the depth of the strip that holds the collar stand, usually 3 to 4 cm at the front and slightly less at the back. A 4 cm band with a stiff fuse stands up under a tie. A 3 cm band in soft cotton collapses, which is fine without a tie and untidy with one.

Read the construction notes before the size. A fused collar keeps its shape through washes and bubbles eventually; an unfused one softens and lasts longer if it is pressed. Spec sheets list the interlining, and fabric weight tells you how much the cloth will move in the wash.

Fit is decided by two numbers: neck circumference plus ease, and sleeve length from the shoulder seam. Everything else is style.