Hair extensions are made from a range of human and synthetic fibers.

Synthetic fibers include Kanekalon and Toyokalon and can differ from brand to brand. Synthetic hair is generally far less expensive than human hair and is available in a wide array of colors and textures, from natural to extraordinary. However, when considering hair extensions it must be kept in mind that since synthetic hair cannot withstand hot temperatures, straightening and curling the hair will not be an option as it will singe.

Human hair is available in many different grades and may be advertised by ethnic origin; India, mainland China and other countries in continental Asia are the top suppliers for 'virgin' unprocessed hair.