Quick answer
Use 2.5–4.5 tog for warm summer rooms, 7.5–10.5 tog for spring/autumn or heated bedrooms, and 12–13.5 tog for cold winter rooms. Hot sleepers generally need less; young children need age-appropriate guidance rather than the adult chart.
Tog rating by typical use
| Tog | Typical use | Room context | Best for |
|---|---|---|---|
| 2.5–4.5 | Summer | Warm or hot room | Hot sleepers and warm nights |
| 7.5 | Late spring / early autumn | Mild room | Flexible transitional warmth |
| 10.5 | All-season / mild winter | Moderate or heated room | Most average sleepers |
| 12–13.5 | Winter | Cool bedroom | Cold sleepers and winter nights |
| 15 | Very cold conditions | Unheated, very cold room | Only sleepers who genuinely need high insulation |
What tog actually measures
Tog is a measure of thermal resistance: a higher number slows heat loss more. It does not tell you how heavy, breathable, durable or luxurious a duvet is.
A lofty down duvet can achieve warmth with less physical weight than many synthetic products. Compare fill construction alongside tog, especially if you dislike heavy bedding.
In technical terms, 1 tog = 0.1 m²·K/W. F. T. Peirce and W. H. Rees of the Shirley Institute in Manchester developed it in 1946. John Lewis, Marks & Spencer and Dunelm explain tog as Thermal Overall Grade. This is a common retail explanation, not the unit's official full name.
Marks & Spencer says weight and thickness do not directly correlate: a thin duvet can have a higher tog, depending on its filling. John Lewis notes that a synthetic duvet can weigh more than one with a high down content at the same tog.
- Higher tog means more insulation
- Tog is not the same as fill weight
- Two fills can share a tog but feel different
- Breathability still matters to hot sleepers
Choose for the room, not the calendar
Bedroom temperature is more useful than the month. A centrally heated flat may need less insulation in January than a cool stone house needs in October.
If your room changes significantly, an all-seasons pair—often a light and medium duvet that fasten together—gives more flexibility than one very warm duvet.
Retailers use different bands. Marks & Spencer lists 1–4.5 tog for summer, 7.5–10.5 for spring and autumn, and 12–15 for winter; it calls 13.5 one of the warmest options. Dunelm calls 7.5–12.5 tog medium and suitable all year round. If you want one duvet for the whole year, that middle band is a starting point, but bands differ by retailer, so check the chart of the one you buy from.
All-seasons sets give you two duvets to use separately or together. Marks & Spencer pairs 4.5 + 9 tog, giving 13.5 tog together for cold winter months. Dunelm pairs 4.5 + 10.5 tog, giving 15 tog together. Marks & Spencer says to use the duvets together for cold winter months and separately for summer. Dunelm describes the 10.5 tog duvet as suitable for colder nights and the 4.5 tog for warmer evenings.
- Warm room: 2.5–7.5 tog
- Moderate room: 7.5–10.5 tog
- Cool room: 10.5–13.5 tog
- Variable room: consider an all-seasons pair
Adjust for the sleeper
Hot sleepers should start below the seasonal default and favour breathable shells and moisture-managing fills. Cold sleepers can move up one warmth band before adding multiple loose blankets.
Babies and young children regulate temperature differently. Use age-specific safe-sleep advice and the product manufacturer's age guidance rather than applying an adult tog chart.
For couples who need different warmth levels, John Lewis describes dual-tog duvets with a different tog on each side. Dunelm calls its 7.5–12.5 tog medium band suitable for sharing, though your warmth needs may differ.
The Lullaby Trust advises no pillows or duvets in the cot before 12 months. Use only lightweight bedding firmly tucked in no higher than the shoulders, or a baby sleeping bag, and avoid letting the baby get too hot. After that, Dunelm suggests a light 3–4.5 tog for toddlers and 4.5–9 tog for children over 3, depending on the season. Check the manufacturer's age guidance.
- Hot sleeper: reduce insulation
- Cold sleeper: increase one band
- Couples: consider two separate duvets
- Children: use age-specific safe-sleep guidance
Frequently asked questions
Is 10.5 tog for summer or winter?
A 10.5 tog duvet is usually an all-season or cooler-bedroom choice rather than a hot-summer duvet. It suits many UK bedrooms in spring and autumn and some well-heated winter rooms.
Source: John Lewis, Dunelm, Marks & Spencer
How many tog should my duvet be?
Match tog to room temperature and personal warmth: roughly 2.5–4.5 for warm summer rooms, 7.5–10.5 for transitional seasons or moderate rooms, and 12–13.5 for cold winter bedrooms.
Source: John Lewis, Dunelm, Marks & Spencer
Is 13.5 tog warm enough for winter?
For many adults in an unheated or cool UK bedroom, 13.5 tog is a warm winter option. Hot sleepers or centrally heated rooms may be more comfortable around 10.5 tog.
Source: John Lewis, Dunelm, Marks & Spencer
Is 7.5 tog too warm for summer?
It may be too warm during hot spells, especially in an upstairs bedroom. It can work in a cool summer room or for a cold sleeper, while 2.5–4.5 tog is the usual warm-weather range.
Source: John Lewis, Dunelm, Marks & Spencer
What does tog mean on a duvet?
Tog is a unit of thermal resistance: 1 tog = 0.1 m²·K/W, and a higher number means more insulation. Marks & Spencer and John Lewis use Thermal Overall Grade as the retail explanation; it is a commercial backronym.
Source: Marks & Spencer, John Lewis, Wikipedia: Tog (unit)
What tog is an all-seasons duvet?
An all-seasons set has two duvets you can use separately or fasten together. Marks & Spencer pairs 4.5 + 9 tog, giving 13.5 tog together; Dunelm pairs 4.5 + 10.5 tog, giving 15 tog. For one duvet to use all year, Dunelm lists its 7.5–12.5 tog medium range as suitable.
Source: Marks & Spencer, Dunelm, Wikipedia: Tog (unit)
What tog duvet should a toddler use?
The Lullaby Trust advises no duvets or pillows before 12 months; use lightweight bedding firmly tucked in no higher than the shoulders, or a baby sleeping bag. Dunelm suggests a light 3–4.5 tog duvet for toddlers and 4.5–9 tog for children over 3, depending on the season. Check the manufacturer's age guidance.
Source: The Lullaby Trust, Dunelm
Sources and methodology
We cross-checked practical guidance against manufacturer care instructions and established editorial or standards sources. Always follow the sewn-in care label on your own product.