Princess seams are long shaped seams which can be found on the front or back of a garment. They are usually used specifically in women's fashion, since princess seams are designed to make a garment fit smoothly and snugly. Many form fitting garments such as formal gowns are made with princess seams. As a general rule, princess 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 in to highlight a slender waist and flaring back out again at the hips. Princess 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 princess seams. On slender and thin women, they can be used to highlight the figure, and provide the illusion of curves. Especially on women with classical hourglass figures, princess seams emphasize the thin waist in a way which many people find aesthetically pleasing. On fuller figured women, princess seams can be adjusted to fit an ample bosom and hips which creating an aesthetically pleasing garment. Many plus size manufacturers use princess 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 princess seams 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. If you aren't sure whether a garment has princess seams or not, 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 which has been specifically designed for princess seams. These patterns can be easily adjusted to fit various figures. If you have an unusual figure, you may want to trace the pattern onto a large sheet of muslin and cut the muslin with very large seam allowances. Fit the muslin on your body with pins, making adjustments where needed, and then use the muslin as a customized pattern. If everything goes awry, you still have the original paper pattern to work with.