A French curve is a template usually made from metal, wood or plastic composed of many different curved segments. It is used in manual drafting and in fashion design to draw smooth curves of varying radii. The curve is placed on the drawing material, and a pencil, knife or other implement is traced around its curves to produce the desired result. They were invented by the German mathematician Ludwig Burmester and are also known as Burmester (curve) set.
French curves are used in fashion design and sewing alongside hip curves, straight edges and right-angle rulers. Commercial clothing patterns can be personalized for fit by using French curves to draw neckline, sleeve, bust and waist variations.