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Duvet Tog Ratings

The tog rating is a human-friendly system used to indicate the warmth of duvets (quilt), sleeping bags, etc. It is mainly used in the UK.

Togs Explained

What Are Togs?

So what is a tog? In technical terms, tog ratings measure thermal resistance. This in effect refers to how good an item is at keeping you warm on a cold night. Duvets with a higher tog value are more suited to colder winter nights whereas low tog values are usually best for warmer summer nights.

Speaking of "suited", this is apparently the origin of the word "tog"; the name comes from the informal English word "togs" for clothing. The fabric of a typical man's suit has a thermal resistance of around 0.1 m2K/W. Since, like many SI units, that's horribly inconvenient for ordinary people it was called "one tog". So "one tog" is about the same warmth as wearing a suit (but nothing else!).

The tog was invented by workers at the Shirley Institute, Manchester, in the 1940s. Tog values are used to measure the potential warmth of many products, not just duvets.

Note that the tog rating does not necessarily relate directly to the thickness of the duvet. Different materials have different thermal resistance characteristics and different thicknesses will be required to achieve the same tog rating.

Tog Values

Most duvets you can buy in the UK vary in tog rating from as low as 4 to as high as 15.

A lightweight summer duvet will usually have a tog rating of around 4 or 5. A medium warmth duvet will probably have a tog rating of around 9 to 11. A winter duvet is likely to be rated from 12 togs upwards. These are typical values for adults - individual needs and preferences will of course vary.

How Are Togs Measured?

With a togmeter, of course!

Yes, really. Despite the somewhat ridiculous name, a togmeter is a precision piece of apparatus capable of measuring tog ratings in accordance with British Standard BS5335 (1984). http://www.here-be-dreams.com/bedroom/togs.html