One duvet is the wrong shape of answer for your room
A single wool duvet is the wrong fit for a room that swings from cold winters to hot summers, because no one weight covers both, so plan on two.
Updated .
In short: Keep a light wool duvet for summer and a heavier one for winter, the same size, and tie them together on the coldest nights.
The quiz sent you here because your room drops below about 67°F on winter nights and rises above about 68°F on summer nights. Wanting one duvet asks it to span that whole range, and the published figures say no single weight can. Changing the fill does not fix this. The tog scale is one British Standard for every duvet, so the gap between a summer weight and a winter weight stays the same whatever is inside. Before you settle on anything, read how a two-weight wool duvet system works and how GSM converts to tog.
The band
| Specification | What this room needs | Source |
|---|---|---|
| GSM | A 200 gsm duvet for summer and a 300 gsm duvet for spring and autumn, tied together for winter | Maker's published two-piece set |
| Tog band | A light duvet near the bottom of the tog scale for summer, and a pair that reaches the winter end of the scale | IDFL tog explanation |
| Construction | Two separate duvets, each with wool encased in cotton, that can be joined or used separately | Maker's published two-piece set |
| Size | Both pieces the same size, so the corners line up when they are joined | |
| Care | Air and spot clean. One seller states its wool duvets are not machine washable, because washing can make the wool felt or shrink | Seller's care FAQ |
Why the answers settle on this band
A tog measures how well a duvet holds heat. A testing lab's summary of the British Standard puts an adult winter duvet between 10 and 15 tog, with a summer duvet well below that (IDFL). Winter in this room needs the top of that scale, and summer needs the bottom. No weight in between does both jobs. A duvet heavy enough for January would be far too warm in July, and one light enough for July would leave you cold in January.
Wool narrows the gap but does not close it, because a thicker wool duvet still holds more heat than a thin one. Two duvets solve the problem without much fuss. One published set pairs a light summer duvet with a heavier one for spring and autumn, and ties the two together for winter. That makes three weights from two pieces, so each season gets the weight it needs.
What would shift the band
If your winter bedroom stays mild, the light duvet may carry you through the year, and the second becomes a spare for cold snaps. If your summer nights run warm rather than hot, the heavier piece may stay on the bed longer into spring and autumn. If the duvet must go in a washing machine, the choice narrows to treated washable wool, which changes how it feels and what it costs. If wool jumpers make you itch, the fill sits inside a cotton shell, so it does not rest on your skin.
Trying the weight on your bed
Put a thermometer by the bed on a cold winter night and again on a hot summer night. The quiz bands are only as good as the readings fed into them. Check that both duvets are the same size and have ties or loops at the corners, or the pair will not join. Read each label for a gsm figure and the care instructions, not only a season name. Most wool duvets are meant to be aired and spot cleaned, and the guide to washing wool comforters covers what to do when that is not enough. For a queen or king mattress, see how a wool duvet insert fits its cover. Then start the season under the light duvet alone. Add the second when you wake cold.
Further on wool duvets
- How does a two-weight wool duvet system work across the seasons?
- How do you convert a wool duvet's GSM to tog?
- What does a wool duvet do with heat and damp, hour by hour through the night?
Sources
Outside reading behind this wool duvet page, each entry marked with where on the page it is used.
- Maker's published two-piece set (nznature.co.nz), used under “The band”; “Why the answers settle on this band”.
- IDFL tog explanation (idfl.com), used under “The band”; “Why the answers settle on this band”.
- Seller's care FAQ (dooleyswool.ie), used under “The band”.