Making Sense of Button Sizing
Q: I would like to order buttons online but am confused by the sizing. Can you explain how buttons are measured?
A: Threads Senior Technical Editor Carol J. Fresia replies: It’s tricky when you have the buttons in hand, but even more so when working with online descriptions. There are three common ways to designate a button’s size, and manufacturers and retailers seem to use any or all of them.
Since the majority of buttons are round, they are measured by diameter. Other button shapes are usually measured along their longest dimension. The measurement may be given in inches, millimeters, or “ligne,” abbreviated as “L,” or some combination of these. One ligne is equal to 1/40 inch. This unit was developed in the late 18th century. (Lignes are also used in watchmaking and to measure the width of men’s hatband ribbons, but in those cases, the unit is closer to 1/12 inch.)
Converting dimensions from one unit of measure to another is almost guaranteed to produce variation in the listed button size, due to changing from fractions to decimals and back again, and rounding up or down along the way. Charts I’ve consulted, for example, designate an 8-mm button as 12L or 14L. One ligne is small at approximately 0.635 mm, so the difference is minuscule. Millimeters or sixteenths of an inch are the smallest units marked on most standard measuring tools intended for sewing, therefore, they are the most practical units to use when selecting a button size.
Note that these measurements account for only the diameter of the button and are most useful for flat buttons. If you’re replacing a garment’s flat buttons with thicker, rounded, or domed buttons, you may need to select a smaller diameter so they can fit through the existing buttonholes.