Princess seams are long, shaped seams that can be found on the front or back of a garment. They are usually used specifically in women's fashion, since they are designed to make a garment fit smoothly and snugly. Many form fitting garments, such as formal gowns, are made with this type of seaming, and as a general rule, the seams are used instead of darts, although the two may sometimes be found on the same garment.
When princess seams are used on the front of a garment, they run over the line of the bust to create an even, smooth look. They usually descend down the front of the garment, gathering the fabric to highlight a slender waist and flaring back out again at the hips. The seams on the back of a garment do essentially the same thing, starting wide at the shoulders and curving in before flaring at the hips.
There are a number of applications for such seams. On slender and thin women, they can be used to highlight the figure, and provide the illusion of curves. Women with classical hourglass figures often find that princess seams emphasize the thin waist in a way that many people find aesthetically pleasing. On fuller figured women, they can be adjusted to fit an ample bosom and hips, creating an aesthetically pleasing garment. Many plus size manufacturers use these seams for this reason.
Wedding gowns and other formal dresses often use princess seams, since they tend to look elegant. Other garments such as women's sportswear may use them as well because they made the garment snug, which can be important with some exercise wear. The form fitting seams are also used on tailored shirts, since they ensure a smooth and attractive fit. Shoppers who aren't sure if a garment has princess seams or not should look for two long, bow-shaped seams running down the front or back of the garment.
Making a garment with princess seams requires the use of a pattern that has been specifically designed for this type of construction. These patterns can be easily adjusted to fit various figures. A sewer who has an unusual figure may want to trace the pattern onto a large sheet of muslin and cut the muslin with very large seam allowances. She can then fit the muslin on her body with pins, making adjustments where needed, and then use the fabric as a customized pattern. This way, if everything goes wrong with the project, she will still have the original paper pattern to work with.