Tog (unit)

It is commonly used in the textile industry and often seen quoted on household items such as duvets, sleeping bags and carpet underlay.

F. T. Peirce and W. H. Rees, of the Shirley Institute in Manchester, England, developed the tog in 1946 as more convenient alternative to the SI unit of m2⋅K/W, writing in their paper The Transmission of Heat Through Textile Fabrics – part II: [1] The results given in this paper are expressed in terms of watts, °C and metres.

with a flux of 1 watt per square decimetre.Peirce and Rees do not give any explanation in their paper for their choice of the term "tog", nor its derivation.

"[1] It is possible that Peirce and Rees chose "tog" as a three-letter term, mirroring "clo", based on the informal word "togs" meaning "clothing", which according to the Oxford English Dictionary is a contraction of the 19th century thieves' cant word togeman, cognate with toga, meaning "cloak or loose coat".

When joined together using press studs around the edges, or Velcro strips across each of the corners, they become a 13.5 tog winter duvet and as such can be made to suit all seasons.