Which duvet tog should I use in summer?

Duvets are sold on a single number, and that number answers only half the question. Two duvets at the same tog can feel completely different on a warm night depending on what is inside them, because how well a filling moves moisture away matters as much for comfort as how well it holds heat in. Getting both right is what stops you waking up damp at three in the morning.

Step by step

1. Understand what tog measures.Tog is a measure of thermal resistance — how well the duvet stops heat escaping. It says nothing about weight, quality, filling type or breathability. A heavy duvet is not necessarily a warm one, and a light one is not necessarily cool.
2. Use the standard ladder as a starting point.Roughly: 4.5 tog or less for summer, around 7.5 to 10.5 for spring and autumn, and 13.5 or more for winter. All-seasons sets pair a 4.5 with a 9 or 10.5 that button together to make a winter weight, which is genuinely the most economical way to buy duvets.
3. Treat the filling as the second half of the decision.Down and feather is the most breathable, moving moisture away efficiently, so it sleeps cooler than its tog suggests and is the best choice for someone who overheats. Wool is excellent at regulating temperature and handling moisture, and is a strong summer option. Synthetic hollowfibre and microfibre are cheaper and washable but hold moisture against you, so a synthetic duvet often feels warmer and clammier than the same tog in down. Silk and bamboo-viscose are light and cool but expensive.
4. Consider dropping the duvet entirely in real heat.In a genuine heatwave the right answer for many people is no duvet: a cotton or linen flat sheet, or a lightweight cotton coverlet. It is not a failure to abandon the duvet in August — most of the rest of Europe does exactly this.
5. Match the cover to the duvet.The cover is in contact with you and matters more than people expect. Cotton percale is crisp, breathable and cool; linen is the coolest and most moisture-absorbing option and gets better with washing; cotton sateen feels smooth but sleeps warmer; polyester and poly-cotton blends hold heat and moisture and are the worst choice for a hot sleeper. Buying a linen or percale cover often does more than dropping a tog.
6. Solve the two-people problem properly.If one person sleeps hot and one sleeps cold, separate duvets on the same bed is the standard continental solution and it works better than any compromise tog. Two single duvets on a double bed also ends the pulling.
7. Wash and air it before the season.A duvet stored all winter collects moisture and dust. Wash it if the care label allows, or air it thoroughly outdoors on a dry day. A well-aired duvet lofts better and smells better, and this is the point in the year to do it.
8. Store the winter one properly.Clean, completely dry, and in a breathable cotton bag rather than sealed plastic, which traps moisture and causes mildew and yellowing. Compressing a down duvet into a vacuum bag for months damages the loft.

Tips

• If you sleep hot, change the cover before you change the duvet. Swapping a poly-cotton cover for linen or cotton percale makes a bigger difference than a tog or two.
• Linen feels expensive and lasts many years, softening rather than wearing out. In cost per summer it is often cheaper than repeatedly replacing cheap covers.
• Kick-out heat rather than fighting it: leaving one leg out from under the duvet is a genuinely effective piece of thermoregulation, because the feet shed heat efficiently.
• Duvet tog is not standardised in the same way across every country, so imported bedding may not match UK labelling exactly.
• For a child's bed, follow current guidance on bedding and room temperature rather than tog alone, and remember that infants should not have a duvet at all until the recommended age.

Common mistakes

• Buying on tog alone and ignoring the filling — Breathability is a separate property that no tog number reports. A 4.5 tog synthetic duvet can feel hotter and clammier than a 4.5 tog down one.
• Keeping a polyester or poly-cotton cover on a summer duvet — The cover is what touches you. Synthetic covers trap heat and moisture and undo much of the benefit of a low-tog duvet.
• Storing a duvet in a sealed plastic bag — Trapped moisture causes mildew and yellowing, and compression damages the loft of a down duvet. Use a breathable cotton bag.
• Persevering with a duvet in a heatwave — A flat sheet is a legitimate and often better answer. There is no rule that a bed must have a duvet in August.

Alternatives

• 4.5 tog down or wool duvet: The standard summer answer, and the most comfortable for anyone who overheats because both fillings breathe well and manage moisture.
• 4.5 tog synthetic duvet: Cheaper, washable and hypoallergenic, but holds moisture against the skin, so it often feels warmer and clammier than the tog implies.
• Cotton or linen flat sheet only: The right answer in a genuine heatwave. Light, breathable, washable, and costs almost nothing.
• Lightweight cotton coverlet or waffle blanket: More substantial than a sheet without much insulation. Good for nights that start hot and cool towards dawn.
• All-seasons duvet set: A 4.5 and a 9 or 10.5 that fasten together. Covers the whole year in one purchase and is the most economical option.

Questions people ask