What's Actually Inside Your Duvet? A Fibre-by-Fibre Reality Check

Duvet shopping is a masterclass in vague language. Labels talk about cloud-like loft and breathable comfort, but the useful information is usually buried in small print: what the filling actually is, how much it weighs, and whether it will still feel like a duvet by February. In a British bedroom, where damp air and unpredictable heating are part of the furniture, the fill matters more than the fancy cover.

So let's strip it back. Here is a no-nonsense look at the four fills you will see most often, and which ones actually earn their price.

Hollowfibre: cheap, cheerful, and prone to going flat

Hollowfibre is polyester. It is the budget workhorse of the duvet world, and there is nothing wrong with that. A decent hollowfibre duvet traps air well at first, feels pleasantly puffy, and costs very little. It also dries faster than wool or down, which matters if your flat has no tumble dryer and the airing rack is already full.

The catch is longevity. Cheap hollowfibre tends to lose loft after a couple of seasons, especially if you wash it often. The filling can clump, leaving cold patches and a duvet that looks tired by the end of winter. It is fine for a spare room or a short-term rental. It is not the fill I would choose for a bed used every night if I wanted it to last.

Rough cost: £25 to £40 for a double, realistically replaced every two years. That is £12 to £20 a year. Not bad — until you factor in the annoyance of buying again.

Microfibre: the synthetic that earns its place, sometimes

Microfibre is also polyester, but the fibres are much finer. That gives it a softer hand-feel and, in better versions, a lighter warmth-to-weight ratio than standard hollowfibre. It dries quickly and washes reasonably well, which makes it a sensible option for damp flats and busy households.

But microfibre is not automatically better. Some duvets sleep warm and clammy because the fabric and filling do not let moisture escape. Cheap microfibre can pill and flatten just like hollowfibre. Look for a cotton casing and a care label that allows a proper wash, not just a cool sponge-down.

On the allergy front, synthetic fills are often marketed as hypoallergenic. That is only half the story. Dust mites live in any bedding where skin flakes and humidity collect, so washing at 60°C where possible, using protectors and ventilating the room matter more than the fibre name on the tag.

Rough cost: £45 to £80 for a double, lasting around four years with care. That is £11 to £20 a year. A good microfibre duvet is one of the quiet winners of the UK bedding market.

Wool: brilliant in a well-ventilated bedroom, frustrating in a damp flat

Wool is the regulator. It absorbs and releases moisture, which helps it feel comfortable across a wider temperature range than polyester. It is a lovely choice for people who overheat under synthetic duvets but do not want the price of down.

The problem is the British flat. Wool is heavier than down for the same warmth, and it dries slowly. In a bedroom with condensation on the windows, wool can feel slightly clammy if the room is not aired properly. Washing is also a faff: some wool duvets are machine washable on a wool cycle, but many prefer professional cleaning.

If you have a draughty bedroom and you sleep neither hot nor cold, wool is excellent. If your windows stream every morning, fix the ventilation first. Wool will not solve a damp room.

Rough cost: £100 to £160 for a double, lasting around eight years. That is £12.50 to £20 a year, plus any cleaning. Reasonable, but only if you look after it.

Down: the warmth-to-weight winner, with a maintenance bill

Down clusters trap air brilliantly. That is why down duvets feel light but warm, and why they cost so much. A good down duvet is packable, long-lasting and genuinely pleasant to sleep under. For many people, it is the best sleep experience on this list.

It is also the fill that punishes neglect. Damp down loses loft, smells musty and takes ages to dry. Washing at home is possible but risky; professional cleaning every few years adds to the cost. Check for responsibly sourced down, and look at the construction: baffle-box duvets keep the filling evenly distributed, while cheap stitched-through versions create cold spots.

Allergy advice is often muddled. Good quality down that is cleaned and encased is fine for many people, but dust mites remain the real issue in most British bedrooms. A down duvet is not a free pass on washing and ventilation.

Rough cost: £200 to £350 for a double, lasting twelve to fifteen years. That is £15 to £25 a year plus cleaning. It can be the best value on the list if you care for it. It is terrible value if it lives in a damp cupboard.

The damp flat factor

British homes, especially flats, have a moisture problem. Drying laundry indoors, closed windows and cold external walls all add up. Every fill needs air, and a duvet pressed against a cold wall can collect condensation. Air bedding weekly, use a dehumidifier if you have one, and open windows when you can.

Dust mites thrive in humid air. Washing bedding at 60°C, using mattress and pillow protectors, and keeping humidity down will do more for allergy comfort than paying extra for a particular fibre.

Real cost per year, not cost per tag

A quick comparison for a double duvet, using realistic UK prices and lifespans:

Fill	Typical price	Realistic lifespan	Rough annual cost
Hollowfibre	£30	2 years	£15
Microfibre	£60	4 years	£15
Wool	£130	8 years	£16
Down	£280	14 years	£20 plus cleaning

Pillows matter too. A cheap hollowfibre pillow may need replacing every year or two; a better microfibre or down pillow can last longer. The annual cost is usually similar, but the nightly comfort is not.

Which one actually earns its price?

For a damp rented flat, a good microfibre duvet is the sensible buy. It dries quickly, washes well and does not cost a fortune. For a well-ventilated home where you want temperature regulation, wool is lovely. For a long-term investment and the best warmth-to-weight, down wins — if you will actually air it and clean it. For a guest bed or a tight budget, hollowfibre is fine.

The fill you should avoid is the premium-priced down alternative that is really just polyester with better marketing. Look at the casing, the stitching, the tog rating and the wash label. That is where the honest information lives.