A light wool duvet, low in weight and tog, for a mild room
If your bedroom stays above about 67°F on winter nights, a light wool duvet of low weight and tog is enough for you all year.
Updated .
In short: A wool duvet of about 200 to 300 gsm suits a bedroom that stays mild in winter, and you can usually keep it on the bed all year.
You land on this result because your bedroom stays mild even in winter. That answer caps the warmth the duvet ever has to supply, and the other answers only move the choice within the band below. Most mild rooms fit it.
The band
| Row | Specification | Source for the figure |
|---|---|---|
| GSM | About 200 to 300 grams of wool fill per square metre | Piglet in Bed lists its lighter weight at the low end of this range; Urban Wool lists its lightweight at the top end |
| Tog band | About 3 to 7 tog equivalent | Urban Wool gives this equivalent tog range for its lightweight |
| Construction | Wool fill in a woven cotton casing, stitched into boxes so the fill stays spread | No figure stated |
| Size | The mattress size, with enough overhang to cover both sleepers | No figure stated; see how a wool duvet insert fits its cover |
| Care | Airing and spot cleaning, with machine-washable wool as a smaller group | No figure stated |
The makers quoted here call these tog figures approximate, not tested values.
Why the answers settle on this band
A mild winter room is enough reason on its own to choose a light duvet. One wool maker's US guide advises a low tog for warm bedrooms, and it pairs that advice with its lighter weight. Nights in a mild winter room sit right at that line. On the British scale, a textile testing laboratory puts a summer duvet at around 4.5 tog (IDFL), and the light wool band straddles that figure.
The summer answer sets the position. If your summer nights stay cool, you can keep the same duvet on all year, and the heavier end of the band gives you a little more margin in January. If summer runs warm, the band narrows and the lighter end is the safer single duvet. In a hot summer room even a light duvet can be too much. On those weeks, fold it back and sleep under a sheet rather than giving up warmth for the rest of the year. Wool takes up sweat as vapour through the night and lets it out into the room, and the heat leaves with that damp, which is why it helps on warm, humid nights, as the hour-by-hour moisture guide explains.
Wanting one duvet means the band has to span your whole year, and in a mild room it usually does. Being open to two duvets matters more when summers are hot, because a mild winter rarely calls for a heavier one, and the two-duvet guide sets out when a pair is worth having.
Airing and spot cleaning is how most wool duvets are meant to be kept, so every construction in the band stays open. Machine-washable wool duvets do exist, and one seller says its duvets can be machine washed, but they are a narrower group, as the guide to washing wool duvets explains.
If wool against your skin can bother you, keep in mind that the fill sits inside a woven cotton shell, so the wool never touches you. That is why many people who find wool jumpers itchy sleep under wool without noticing it.
What would shift the band
A colder winter changes the result first. If the bedroom drops below that winter line on cold nights, one light duvet will run cold and a heavier weight belongs in the band. How you sleep also shifts where you land. A warm sleeper can stay at the light end even with a cool summer, while a cold sleeper may want the heavier end or a blanket on top. If the heating switches off overnight, that counts too, because the coldest hour before dawn sets the temperature the duvet has to cover.
Trying the weight on your bed
Put a thermometer near the pillow for a few nights in the coldest month and again in the warmest. Read it in the early morning. That is when the room is usually at its coldest. On a label or product page, look for the gsm figure, because some sellers state only the applicable season instead (Scooms). Treat any tog figure for wool as an approximate equivalent, since wool duvets aren't rigidly defined by tog rating. The GSM and tog conversion guide explains how the two numbers relate. If your readings stay above the winter line, you can stay within the light band.
Further on wool duvets
- How do you convert a wool duvet's GSM to tog?
- How is a wool duvet built, layer by layer?
- 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.
- Piglet in Bed (us.pigletinbed.com), used under “The band”; “Why the answers settle on this band”.
- Urban Wool (urbanwool.co.uk), used under “The band”; “Why the answers settle on this band”.
- IDFL (idfl.com), used under “Why the answers settle on this band”.
- Scooms (scooms.com), used under “Trying the weight on your bed”.