Winter Tog Duvets: Everything You Need To Know

Do you find duvet tog ratings a mystery? We will answer your questions and more, unveiling the secret of tog ratings and making sure you are warm through the approaching winter nights.

We cover, and much more: 

  • Are weight and warmth part of the tog value?
  • What is the highest tog rating you can get?
  • What tog is for all-year use?
  • How to increase your warmth in bed.

Settle in as we start.

What is a tog value?

Tog is a unit of thermal insulation of a given area. There is more to tog values than meets the eye, so don’t think for one moment it is a bunch of guys just sleeping under duvets in the cold and comparing notes.

Tog was developed by the textile industries Shirley Institute in Manchester way back when to standardise the warmth of materials.

The name tog is thought to come from the Greek toga, meaning clothes.

Do you know there is a formal calculation for your duvets tog value? The basic unit of insulation coefficient is the RSI, (1 m2K/W). 1 tog = 0.1 RSI.

A tog is 0.1 m2K/W. In other words, the thermal resistance in togs is ten times the temperature difference (in °C) between the two surfaces of a material when the heat flow is equal to one watt per square metre.

What is the highest duvet tog?

15 is the highest tog value for your duvet. Tog values start at 1, which is the lowest rating and could be used on a balmy summer’s night.

However, if you need an extra warm duvet for the winter, you will be hard pushed to find a tog rating higher than 13.5, which should be more than adequate for providing warmth.

Below is the common table representing the seasons and the recommended tog value for your warmth.

SeasonRecommended tog value
Summer1 – 4.5
Spring/Autumn7 – 10.5
Winter12 – 15
All Seasons10.5

Does duvet weight affect the warmth and tog?

No, various types of fillings are heavier than others. It seems that the heavier a duvet, the higher the tog value, but duvet fillings have different properties.

When you select your duvet for warmth during the winter months, you will be faced with an array of materials that can be overwhelming and confusing.

The warmer duvets trap a lot of air in between the filling. This creates a thermal barrier and is the ideal solution for keeping warm.

If you look at synthetic duvets such as hollowfibre or microfibre, they are lightweight but have exceptional insulation properties that keep you warm on the coldest night.

So, don’t consider the weight of the duvet when making your choice. Trust the tog value.

Do you only need one duvet for all seasons?

In the UK, yes. If you live in a warm or temperate climate, then you may decide to use a couple of different tog values and change as the seasons change.

However, in the UK, it is rare to experience more than a couple of weeks of blisteringly hot weather, and when you do, you ditch the duvet for a bed sheet as anything else would be too warm.

Given the climate uncertainty of the UK climate, it makes sense to select an all-year-round duvet recommended as a 10.5 tog.

The 10.5 togs will provide you with enough warmth on the coldest night, assuming your windows are closed, and there is no draft howling through your home.

But there are other considerations to take into account.

How cold or hot do you run?

It’s not a crazy question. You will not be surprised to find out we are all different, including body temperature.

There has been a debate for some time on how body temperature differs, but there is a premise widely regarded as being accurate, and it’s this.

The lower your muscle mass relative to the surface area of your body can make you feel cold. We know this is true as the elderly reduce muscle; they always seem to be on the chilly side, even on warm days.

Females also tend to sleep on the cooler side, which you can assume is directly correlated to muscle mass compared to males.

If you are in a category that runs cold upgrading your duvet tog, it’s not worth rolling the dice to tough out the long winter nights.

Can you sleep with two different tog values on your bed?

Yes, some more expensive options. If your budget is not constrained, pure wool duvets have the option to tie different tog duvets together.

You could also select two single duvets for a double bed with different tog values; you can kill two birds with one stone, sleep comfortably at your body heat and cease the endless battle for the duvet!

How to know what tog duvet to buy?

Some factors need to be considered. Generally, you can assume the tog rating works perfectly and is reliable.

Select your tog based on the season:

  • 1-4.5 tog. Perfect for warm nights through the summer
  • 7-10 tog. Consider this tog for changing seasons, late spring to early autumn
  • 12-15 tog. For those nights when sleeping in Siberia may seem like a better option
  • 10.5 tog. This is the sweet spot for most sleepers in the UK and northern Europe

Still feeling chilly at night?

Add an extra layer. It sometimes happens when the cold snap arrives that you just can’t get warm enough, so what can you do?

By adding a blanket over the duvet, you will find the insulation increases dramatically and should be more than enough to have a toasty night’s sleep.