Understanding the Tog Rating for a Comfortable Night’s Sleep

Jessica from South Down Duvets tells us the meaning behind that “tog rating” we see on duvets in the UK, and why it can help us to have a more comfortable night’s sleep.

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Like drizzle and strawberries and cream at Wimbledon, Tog is a quintessential English thing and not found in other parts of the world. It simply is a measure of warmth of an item of bedding, especially duvets. But that is where the simplicity ends.

Wikipedia has the following to say about it:

Tog is the basic unit of insulation coefficient is the RSI, (1 m² K / watt). 1 tog = 0.1 RSI. The Shirley Institute in Britain developed the tog as an easy-to-follow alternative to the SI unit of m2K/W. Launched in the 1960s, the Shirley Togmetre is the standard apparatus for rating thermal resistance of textiles, commonly known as the Tog Test.

According to British retailer John Lewis, tog guidelines for duvets are as follows:

Lightweight summer duvet:

4.5 tog

Spring/Autumn weight duvet:

9.0 – 10.5 tog

Winter weight duvet:

12.0 – 13.5 tog

But as one gets to know more about bedding, these tog ratings are guidelines only. The tog rating of an item is affected by a number of factors, not least the type of fibre under consideration. The men in white coats tell me that the highest possible tog rating goes to bubble wrap and lowest goes to cement. All other fibres tog somewhere in between .

Some manufacturers of wool duvets maintain that tog ratings should only be applied to synthetic fibre and not natural fibres like wool and perhaps tog was developed in the 1960s to provide a benchmark for the swiftly emerging synthetic fibres during that decade.

Our best-selling Southdown duvets contain 350gr of pure wool per square metre of duvet. This equates to a 7.4 tog which presents an all-weather, all-year duvet most commonly sold, for example, in Germany.

Our reasoning behind an all-purpose duvet is simple – we don’t expect our customers to have buy two duvets of differing weights to get a decent night’s sleep all year round or to have to buy two light weight duvets and then have to Velcro them together in winter.

But we do have customers who have extreme needs. Thus we have a Lambkin Lite at 4 tog for the hot-blooded among us and we have a Woolly Mammoth at 8-9tog for those who really feel the cold.


Tog Rating vs Comfort Levels


Now an interesting thing about tog is that it measures thermal resistance but not levels of comfort which, with duvets, are two totally different things. Think of how uncomfortable bubble wrap would be to sleep under and cement doesn’t even bear thinking about in terms of comfort! The point is a very warm duvet with a 13.5 tog might appear to be ideal but can turn out to be oppressively heavy, or it might result in disturbing night sweats if it’s synthetic. A feather/down duvet with a medium tog might offer the right warmth but the fill might clump, and cause hot and cold spots in the duvet or aggravate asthma or allergies.

So the message is simple: the ideal solution is something comfortable and of the right temperature of which tog is only a part of the equation.

So don’t let tog bog you down. Go for comfort and Shirley Togmetre will take care of herself. Still unsure? Contact us and let us talk you through it.

By Jessica, South Down Duvets

logo2 Understanding the Tog Rating for a Comfortable Nights Sleep

Edited by Helen Kinsella

Image sourced: South Down Duvets

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