Key takeaways
- From 1 October 2026 the Ofgem cap is £1,723 a year, with electricity at 26.32p per kWh and no VAT on it until 31 March 2027. Gas is 7.97p per kWh including 5% VAT.
- That puts a 2kW plug-in bedroom heater at 52.6p an hour, or £4.21 for an eight-hour night. A 13.5 tog duvet at £19.99 costs less than five of those nights.
- UK fire safety law covers the mattress and the pillow but stops at the duvet. The 1988 regulations define furniture as including “mattresses (of any size) and pillows, but does not include bedding”.
- Nothing on a duvet label has to prove its tog. The mandatory labelling law is about fibre composition, and trading standards enforce that, not warmth.
Britain swapped its duvet this week. On the morning of 21 September 2026 the Amazon UK Home & Kitchen bestseller chart had seven bedding items inside the top 30: a fitted sheet at 5, a mattress protector at 8, a 10.5 tog duvet at 9, a second fitted sheet at 17, a mattress topper at 19, a duvet cover set at 23 and a twin pack of pillows at 30. That is the annual tog change happening in public.
Every duvet guide you’ll read this month prints the same three-line table: 4.5 tog for summer, 10.5 for spring and autumn, 13.5 for winter. It’s fine as far as it goes. What none of them tell you is what the warmth is worth in money, or how little of that number anyone is obliged to stand behind. So we went and read the law and the price cap instead.
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Prices and specs last checked 21 September 2026 · how we picked
The line that runs through your bed
The Furniture and Furnishings (Fire) (Safety) Regulations 1988 are the reason your sofa doesn’t go up like a firework. Regulation 3 defines what counts as furniture, and the definition is worth reading slowly. It covers beds and divans, cots, cushions, high chairs, “mattresses (of any size) and pillows, but does not include bedding”.
So there’s a legal boundary running horizontally through your bed at about the height of your chin. The mattress underneath you has to pass a cigarette test. The pillow under your head has to pass one too. The duvet on top of you has to pass nothing at all. Neither does the cover you put it in, or the sheet under you.
We’re not saying duvets are dangerous. Most are polyester fill in a cotton or polycotton shell and they behave about how you’d expect. The point is narrower and it matters when you’re comparing a £15.25 duvet with a £57.99 one: on fire performance, the law is asking the cheap one and the dear one for exactly the same thing, which is nothing.
The same goes for the tog figure on the front of the bag. The Textile Products (Labelling and Fibre Composition) Regulations 2012 give effect in the UK to the EU fibre-naming regulation, and they’re enforced by local weights and measures authorities in Great Britain and by the Department of Enterprise, Trade and Investment in Northern Ireland. What they compel a manufacturer to tell you is what the thing is made of. Warmth isn’t in scope. A tog number is a trade claim, and you’re taking it on the brand’s word.
You can watch that play out on the listings. Most guides will tell you 13.5 tog is the top of the scale. One of our picks below is sold at 16.5 tog. Both can be true at once when there’s no referee.
What you’re actually buying: the heating you don’t run
Here’s the figure nobody puts next to a duvet. We read the Ofgem price cap page on 21 September 2026. From 1 October to 31 December 2026 the cap sits at £1,723 a year, up 4%. Electricity is 26.32p per kWh with a 54.83p daily standing charge, and there’s no VAT on electricity from 1 October 2026 to 31 March 2027. Gas is 7.97p per kWh including 5% VAT, with a 29.68p daily standing charge. Those are the GB Direct Debit averages.
Run those through a bedroom heater and the arithmetic gets blunt fast.
| What you run in the bedroom | Cost per hour | Eight-hour night | 1 Oct to 31 Dec (92 nights) |
|---|---|---|---|
| 2kW plug-in fan or convector heater | 52.6p | £4.21 | £387 |
| 1kW plug-in heater | 26.3p | £2.11 | £194 |
| 60W electric underblanket, one hour before bed | 1.6p | 1.6p | £1.45 |
| 13.5 tog duvet, bought once | n/a | n/a | £15.25 to £57.99 |
The cheapest duvet in this guide costs about three and a half nights of that 2kW heater. The dearest costs about fourteen. If a warmer duvet lets you leave the bedroom heater switched off through the quarter, it has paid for itself several times over by Christmas, and the sums aren’t close enough to need a calculator.
Gas is the other half of the picture, and it’s why plug-in bedroom heating is the expensive habit. At 7.97p per kWh, and assuming a boiler that’s 90% efficient, a unit of delivered gas heat costs about 8.9p. The same unit from a plug-in electric heater costs 26.32p, so about three times as much. Against that, the gas standing charge of 29.68p a day is £27.31 across the quarter whether you light the boiler or not. Our UK running cost index carries the same rates applied across the rest of the house.
How we picked these
We don’t test duvets. There’s no lab here and we’re not going to pretend otherwise. What we did on 21 September 2026 was read the Amazon UK bestseller chart, search the double-size duvet listings, open every product page to confirm the title, tog, size and buy-box price, and pick six that do genuinely different jobs. Price, tog and size come off the listing on the day. The regulatory points come from legislation.gov.uk and the cost figures from Ofgem, both opened while writing this. Our methodology page sets out the rest.
One thing we deliberately didn’t do is rank by fill power or thread count. Those are numbers the same unregulated label prints, and stacking unverified figures on top of each other doesn’t make a ranking, it makes a guess with decimal places.
At a glance
| Duvet | Tog | Size priced | Price | Fill | Best for |
|---|---|---|---|---|---|
| Silentnight Deep Sleep | 10.5 | Double | £19.99 | Microfibre | The autumn swap |
| Silentnight Deep Sleep | 13.5 | Double | £19.99 | Microfibre | Winter, same money |
| Slumberdown All Seasons 3-in-1 | 4.5 + 9 | Double | £31.50 | Hollowfibre | One duvet all year |
| SleepyNights 13.5 Tog | 13.5 | Double | £15.25 | Hollowfibre | Cheapest way warm |
| SUFUEE Goose Feather & Down | 13.5 | Double | £50.99 | 50% feather, 50% down | Natural fill |
| Lancashire Bedding 16.5 Tog | 16.5 | King | £57.99 | Hollowfibre | Genuinely cold rooms |
Silentnight Deep Sleep 10.5 Tog Double Duvet
£19.99 on 21 September 2026 · microfibre fill · double
This was sitting at number 9 in the entire Home & Kitchen chart when we looked, which tells you what the country is buying in the third week of September. A 10.5 tog is the sensible default for October and November in most insulated UK houses, and at twenty pounds there’s no case for agonising over it.
The catch: microfibre flattens. Give it two or three winters of being scrunched into a cover and the loft goes, and loft is where the warmth lives. Budget for replacing it every few years. This is not a ten-year duvet.
Check price on Amazon →Silentnight Deep Sleep 13.5 Tog Double Duvet
£19.99 on 21 September 2026 · microfibre fill · double
Same range, same shell, three tog warmer, and on the day we priced it, the identical £19.99. That’s the clearest argument in this whole guide. If your bedroom is cold enough that you’ve been reaching for the heater, the tog step costs you nothing here, and the heater costs 52.6p an hour.
The catch: 13.5 tog is too much for a warm modern flat, and overheating wakes you as reliably as cold does. If your bedroom sits comfortably above 18°C without help, buy the 10.5 instead.
Check price on Amazon →Slumberdown All Seasons 3-in-1 Double Duvet, 4.5 Tog plus 9 Tog
£31.50 on 21 September 2026 · hollowfibre · double · made in the UK per the listing
Two duvets that button together. Use the 4.5 in summer, the 9 in spring and autumn, both clipped into 13.5 when it turns. It solves the storage problem as well as the warmth one, which is the real reason people buy these: no second duvet living in a bag under the bed from May to October.
The catch: combined, it’s bulkier than a single 13.5 and the join can shift inside the cover overnight. And the arithmetic only works if the ties actually get used. Plenty of these end up permanently clipped together and used as an expensive 13.5.
Check price on Amazon →SleepyNights 13.5 Tog Double Duvet
£15.25 on 21 September 2026 · anti-allergy hollowfibre · double
Three and a half nights of a 2kW heater, and then it’s yours. This is the pick for a spare room, a student let, or the bedroom of someone who has been putting the heating on because the duvet is thin. At this price the payback question stops being interesting.
The catch: “anti-allergy” isn’t a regulated term on bedding any more than tog is. It generally means a synthetic fill that dust mites like less than feathers, which is useful and is also true of every other hollowfibre duvet here. Read it as a description of the filling and nothing more.
Check price on Amazon →SUFUEE 50% White Goose Feather and 50% Down Duvet, 13.5 Tog
£50.99 on 21 September 2026 · feather and down · double · 300 thread count cotton shell
Down traps more air per gram than polyester does, so a natural-fill duvet at the same tog drapes closer and weighs less. It also lasts, if you look after it. The cotton shell here is a real improvement on polycotton for anyone who sleeps hot inside a warm duvet, because the shell is what moves moisture.
The catch: feather duvets and domestic washing machines get along badly, so you’re looking at dry cleaning or a launderette drum. Quills work their way through the shell eventually. And this is a marketplace brand, so there’s no long warranty to lean on.
Check price on Amazon →Lancashire Bedding 16.5 Tog Winter Duvet
£57.99 on 21 September 2026 · hollowfibre in a cotton blend shell · king, 230 x 220cm
Three tog above what most guides call the top of the scale. If you’re in a solid-wall cottage, a loft conversion or a room where the radiator never quite wins, this is the one that means you can leave the heater off. It’s also the clearest illustration of the point we made earlier: there’s no authority stopping a manufacturer printing 16.5, and no authority confirming it either.
The catch: the price we read is for a king, so it isn’t a like-for-like comparison with the doubles above. It’s heavy, it takes an age to dry, and in any room that reaches a normal temperature you’ll be throwing a leg out by two in the morning.
Check price on Amazon →A duvet is not a heating system
Worth saying plainly, because the money argument above can be pushed too far. NHS winter advice is to heat the rooms you regularly use, including the bedroom, to at least 18°C where you can, and to keep bedroom windows shut at night. It flags that this matters most for people over 65, children under five, anyone pregnant, and anyone with a long-term health condition or disability.
A 13.5 tog duvet keeps the person under it warm. It does nothing for the air in the room, the damp in the walls, or anyone who gets up in the night. If the reason you’re reading this is that heating the bedroom has become unaffordable, the duvet is a sensible move and it isn’t the whole answer. The government’s help with energy bills, grants and benefits is worth checking, and the NHS page above links straight through to it.
If the trouble in your bedroom is condensation, a warmer duvet will make it slightly worse by keeping you in bed longer with the window shut. Our guide to moisture absorbers covers that side. For targeted warmth without heating the room, an electric underblanket at 1.6p an hour or a hot water bottle does more per pound than a plug-in heater. And if the trouble is the opposite one, our cooling bedding guide is waiting for July.
What this guide could not check
We did not measure any of these duvets, and we have no way to confirm that a duvet sold as 13.5 tog delivers 13.5 tog. Nobody outside the manufacturer does. We also could not verify fill power, thread count or the “anti-allergy” and “made in the UK” claims on the listings, all of which come from the seller. Prices were read from the buy box on 21 September 2026 and change daily. We could not open the British Standards pages for the textile thermal resistance test during this check, so we have not named a test method.
Questions people actually ask
What tog duvet do I need for a British autumn?
10.5 tog suits most insulated UK homes through October and November, which is why the 10.5 was the one climbing the bestseller chart on 21 September 2026. Move to 13.5 if your bedroom sits below about 16°C overnight or you’ve been running a heater in there.
Is a warmer duvet cheaper than heating the bedroom?
By a wide margin. At the capped electricity rate of 26.32p per kWh for 1 October to 31 December 2026, a 2kW plug-in heater costs 52.6p an hour and £4.21 for an eight-hour night. A 13.5 tog duvet at £19.99 is a one-off cost equal to under five of those nights.
Does anyone check that a duvet really is 13.5 tog?
Not as a legal requirement. The UK labelling law that applies to textiles covers fibre composition and is enforced by trading standards, and warmth is outside it. Tog is a manufacturer’s claim, which is why you can find duvets sold at 16.5 tog alongside guides saying 13.5 is the maximum.
Do duvets have to meet fire safety regulations?
No. The Furniture and Furnishings (Fire) (Safety) Regulations 1988 define furniture to include mattresses of any size and pillows, and expressly exclude bedding. Your mattress and pillow are covered, your duvet and sheets are not.
Feather and down or synthetic?
Down gives more warmth per gram and drapes better, and it lasts longer if you keep it dry and get it cleaned properly. Synthetic costs a third as much, goes in a domestic washing machine, and suits anyone who’d rather not sleep under feathers. At the prices above, the synthetic duvets pay for themselves against a bedroom heater in days, so the choice comes down to feel and washing.
Sources
- The Furniture and Furnishings (Fire) (Safety) Regulations 1988, regulation 3, legislation.gov.uk. Read 21 September 2026.
- The Textile Products (Labelling and Fibre Composition) Regulations 2012, regulation 3, legislation.gov.uk. Read 21 September 2026.
- Energy price cap unit rates and standing charges, Ofgem. Read 21 September 2026.
- Winter vaccinations and winter health, NHS. Read 21 September 2026.
Prices were read from the Amazon UK buy box on 21 September 2026 and change without notice. Look Into is published by Whito Ltd and earns commission on qualifying Amazon purchases as an Amazon Associate. Commission never changes what we recommend or the order we list it in. See how we make money. This page is general product information and is not financial, legal or medical advice.