A duffle coat, or duffel coat, is a coat made from duffle, a coarse, thick, woollen material. The name derives from Duffel, a town in the province of Antwerp in Belgium where the material originates. Duffle bags were originally made from the same material.

There are many varying styles to the duffle coat, although the most common British style would be composed of the following features:

The wooden toggle-fastenings were made to be easily fastened and unfastened while wearing gloves in cold weather at sea. Current designs have toggles made of buffalo horn, wood or plastic. The oversized hood offered enough room to wear over a Naval cap. After rain, a duffle coat has a characteristic smoky smell.

The duffle coat owes its popularity to the British Royal Navy, who issued a camel-coloured variant of it as an item of warm clothing during World War I. The design of the coat was modified slightly and widely issued during World War II. In the Navy, it was referred to as a "convoy coat". Field Marshal Montgomery was a famous wearer of the coat, as a means of identifying himself with his troops, leading to another nickname, "Monty coat". Large stocks of post-war military surplus coats available at reasonable prices to the general public meant that these coats became a ubiquitous and popular item of clothing in the 1950s and 1960s. The British firm Gloverall purchased surplus military supply of coats after World War II and have continued to still make the Monty ever since and in 1954 started producing their own version of the Duffle coat and continue to do so today still being Made In England. Gloverall made in the 50's what is known as today's Duffle by using leather fastenings and Buffalo horn toggles with a double faced checkback fabric. Every Duffle coat you see today in that configuration is a copy of that original made by Gloverall.