The difference between winter and summer duvets

Winter duvet and summer duvet sound like marketing categories — but the differences are real and measurable. They affect how warm you stay, how well you sleep, and how comfortable your bed feels in different temperatures. Here's what actually distinguishes the two, and how to pick the one that's right for you.

1. The TOG rating
2. Fill weight differences
3. Material differences
4. Which to use when
5. All-season alternative

The TOG rating

TOG (Thermal Overall Grade) measures the duvet's insulation. Higher TOG = warmer:

• 1.5–4.5 TOG — Summer duvet. Light, breathable, minimal insulation.
• 4.5–7 TOG — Spring/autumn weight. Some warmth without the bulk.
• 7–10.5 TOG — Standard winter duvet. Comfortable for most adults in unheated bedrooms.
• 10.5–13.5 TOG — Heavy winter, for cold rooms or very cold sleepers.
• 13.5+ TOG — Mostly old-fashioned, can cause overheating in modern centrally-heated homes.

Most adults sleep best with a 7–9 TOG winter duvet and a 2.5–4.5 TOG summer duvet.

Fill weight differences

Beyond TOG, the actual amount of fill matters. A bamboo winter duvet might have 300–400g/m² of fill, while a summer duvet has 150–200g/m². The summer duvet is physically lighter, drapes more lightly on you, and feels less wrapped. The winter duvet has more fill density, more loft, and creates more of an air-trapping insulating layer.

Material differences

The fill material matters as much as the weight. Some fills are warm but don't breathe (like polyester) — bad in summer, OK in winter. Some breathe well but don't retain heat (like silk) — good in summer, less so in winter.

Bamboo is unusual: it manages both. The fibre's natural thermoregulating properties mean a bamboo duvet keeps you warmer in winter (without overheating) AND keeps you cooler in summer (without losing heat retention when you need it). This is why some people prefer bamboo year-round in different weights — same material, different season-specific densities.

Browse the summer duvet and winter duvet ranges.

Which to use when

Summer duvet: roughly May to September in northern Europe. Bedroom temperatures above 18°C, daytime highs above 22°C, comfortable in light sleepwear.

Winter duvet: roughly October to April. Bedroom temperatures below 18°C, daytime highs below 14°C, comfortable in long-sleeve sleepwear.

The transition periods (March–April, October) are where many people use a mid-weight option, or layer a lighter duvet with an extra blanket.

All-season alternative

Some people prefer a 4-season duvet system — a lighter summer duvet plus a slightly heavier autumn duvet, used together in winter for max warmth. Used separately, each works for its own season. This avoids storing duvets and gives you more flexibility for unusual weather.

For more on the seasonal change, see time for the big duvet change.