Picture a terraced house in February. The heating goes off at eleven, the landing is draughty, and the duvet on the bed is one somebody bought in a sale three winters ago. The sleeper gets up at six with cold feet and a slightly guilty feeling about the thermostat. Often the bed is not the problem at all. The tog number is.
Tog measures how well a duvet traps heat. It does not measure softness, fluffiness or how expensive the cover looks, so two duvets that feel the same can carry very different ratings. Treat the label as the most honest piece of information on the whole product.
How do the tog levels line up?
Most UK retailers sort duvets into rough bands. Around 4.5 tog suits summer or very warm rooms. Around 10.5 tog is the all-year option that many people settle on. 13.5 tog is the figure most often sold for winter, and 15 tog is aimed at people who feel cold easily or sleep in a room that never quite warms up. Brands invent their own names for these bands, so ignore the wording on the packet and read the number.
Which tog for your room?
Start with the room rather than the duvet. A bedroom that loses its heat overnight, or one tucked on the north side of a house, needs more insulation than a room that stays warm until morning. If two people share the bed, the colder sleeper decides the minimum, and a lot of couples solve the problem by buying two duvets so each side gets its own rating.
For most UK bedrooms in winter, 13.5 tog is a good place to begin. If the room is milder than the one in a terraced house, or you simply run warm, 10.5 tog with a blanket on top usually does the job.
Layers beat a single heavy duvet
A very warm duvet can feel stifling in the first hours of the night, when you are still carrying heat from a bath or a long day. Layers solve that. A medium duvet stays on, a throw or fleece blanket sits across the foot of the bed, and you pull the top layer off as the night goes on, all without leaving the warm side of the bed. You also avoid replacing everything when the weather shifts in spring.
What else keeps the bed warm?
A fitted sheet that grips the mattress keeps the duvet from sliding off the side in the night, which is one of the quieter ways cold air gets in. A mattress topper adds a layer between you and a cold base, and it often makes more difference than a new duvet would. Both cost less than a new winter tog, so they are worth trying first.
Checking before you buy
Look at the tog figure, the filling and the care instructions, in that order. Compare the number across brands rather than trusting the word winter in a product name. Read the seller’s returns terms as well, because a duvet is much easier to judge after a few nights at home than under a shop light.
Buying for a guest room or holiday let? Mix the ratings. A lighter duvet suits guests who run warm, and a heavier one covers everyone else. British Wholesales duvets are sold to home buyers and businesses alike, so it is useful to compare its tog options against what you already have. Absolute Home Textiles duvets make a side-by-side comparison straightforward.
A worked example
Take a two-bedroom flat with a single radiator in the main bedroom, which is typical of many older homes. The occupant sleeps alone, feels the cold in the feet and shoulders, and keeps the window cracked for ventilation. For this person, a 13.5 tog duvet with a cotton sheet beneath and a throw folded at the foot makes sense. In a warmer flat with a radiator directly under the window, the same sleeper might be comfortable on 10.5 tog with the throw kept for the coldest nights. The numbers are the same kind of tool; the room is what changes the answer.
Notice how little the duvet’s appearance mattered in that example. The decision came from the room, the sleeper and how much heat the bed was losing, and the label simply confirmed which option fit.
Storing the spare in summer
A winter duvet takes up a surprising amount of space when it is packed away. If you store it, keep it clean and fully dry, and use a breathable bag rather than an airtight one, which can trap damp. Check it once or twice over the summer so it is ready when the first cold snap arrives.
Timing the purchase
Buying in late autumn gives you time to live with a new duvet before the hardest cold arrives. Leaving it until the first frost usually means a hurried choice and a thinner range of sizes. If the one you own is clearly wrong, sorting it now is the easiest fix you will make all year.