Sewing pins are small pieces of metal wire used in attaching fabric and classified as sewing notions. Sewing pins have several uses. They hold layers of material in place both prior to and during attachment. When an item is being fitted, sewing pins are used to determine where a line of stitching should fall. Some sewing pins are designed to be multipurpose, either for use in another craft or for other purposes.

Two Main Types. The two main types of sewing pins are straight pins and safety pins, also known as hemming or basting pins. The key facets of these two types of sewing pins that differ and can help you choose the type you need are: length, thickness, type of head and tip for straight pins, and whether they are straight or curved for safety pins. For both kinds of sewing pins, the metal or finish is typically brass, steel, nickel, or a combination thereof. The metal used determines whether the pins will stick to a magnet –- a plus for making sure there are none on the floor. Nickel-plating helps prevent steel pins from rusting.

Heads and Tips. The typical pinhead on the straight pin is a blunt nub made of the same metal and called a flat head. Straight pins are also available with larger color ball heads made of plastic or glass, making them easier to see and grasp. T-pins have a head bent into the shape of a capital letter T, making them also easier to grasp and see. Straight pins come standard with pointed tips, but ballpoint tips are available to avoid catching threads when working with knits.

Length and Width. Metric and imperial pins are made to different specifications and are not exactly equivalent. Pins made in the US are categorized by a size number and length in inches to the nearest 1/16 inch. The sizing systems are different for straight pins and safety pins. Metric pins are not categorized by a size number, but rather by length in millimeters to the nearest millimeter.

Imperial straight pins are offered in sizes ranging from ½ inch to 1¾ inches (~1.3 mm to 4 mm), with each size corresponding to an increase in 1/16 inch (~1.6 mm). The most common sizes are 8, 16, 17, 20, 21, 22, 24, and 28. One oddity to note with regard to T-pins is that, while they are available in sizes 16, 20, 24, 28, and 32 -- the longest T-pin at 2 inches (~51 mm) -- size 28 T-pins are sometimes referred to as “extra long.”

Imperial safety pins are sized as follows (~19–76 mm):

• Size 00 = ¾ inch
• Size 0 = 7/8 inch
• Size 1 = 1 7/16 inches
• Size 2 = 1 ½ inch
• Size 3 = 2 inches
• Size 4 = 3 inches

Notice that the increase in length is not equivalent as the size goes up. Size 4 safety pins are also known as blanket pins.

For metric straight pins, typical sizes are 13, 25, 26, 30, and 34 mm (~0.5 to 3.7 inch). Metric t-pins are often offered at a 44 mm (~1.7 inch)length, and safety pins at 37 mm (~1½ inches) and 46 mm (~1.8 inches). Descriptions of metric pins are more likely to include the thickness and offer more variety in that area, while imperial pins seem to be available in a greater number of lengths.

In general, longer pins tend to be thicker, made for coarser fabrics. Dressmaker or seamstress pins are the most common, and are designed for fabrics of light- to medium-weight. Pleating pins are a bit shorter and extra fine, suitable for delicate fabric. Very short pins, often called appliqué and sequin or sequin pins, are some of the shortest pins offered. Another type of straight pin is the bridal and lace pin.

Differentiating Pin Types. Sewing pins are differentiated from specialized pins for other tasks, including quilting pins, flower or corsage pins, kilt pins, a knitting stitch holder that looks like an oversize safety pin, hat pins, bobbin lace pins, and diaper pins. There are also fork pins, sometimes known as upholstery pins or loose cover pins, that are shaped like a U. Tidy pins, also called twist pins or upholstery pins, have a top like a thumbtack and a helix shaped shaft, and are specially designed to hold slipcovers, mattress pads, and doilies in place. Notice that the name upholstery pins is used for two quite different items.