Thinsulate is a brand of synthetic fiber thermal insulation used in clothing. The word is a portmanteau of the words thin and insulate, trademarked by 3M.^[1] The material is made by the 3M Corporation and was first sold in 1979.^[2] It was originally marketed as an inexpensive alternative to down; at the time, 3M claimed it was twice as warm as an equivalent amount of any natural material.^[3][4]

Originally designed for clothing, it later became popular as an acoustic damping material.^[5] In 1997, 3M generated US$150 million in annual revenue from the product.^[5] Its development originated from other microfibre products made by 3M.^[6] It has been used in US army clothing since the mid 1980s.^[7]