Duvet Tog Calculator
Match a duvet’s tog rating to the season and your bedroom’s night temperature, so you stay warm in winter without overheating in summer.
Warmth is a number, not a guess
Most people own one duvet and quietly suffer half the year — too hot in July, not warm enough in January. Tog ratings exist precisely so you can match the duvet to the conditions, and the two conditions that matter are the season and how warm your bedroom actually runs at night. A hot sleeper in a heated flat and a cold sleeper in a draughty cottage want very different togs for the same month.
Pair the right duvet with the right cover using the Bedding Size & Fit Calculator, and check your sheet quality with the Sheet Thread Count Guide.
Frequently Asked Questions
What is a tog rating?
A tog is a unit of thermal resistance — how well a duvet traps warmth. The higher the tog, the warmer the duvet. Ratings typically run from about 2.25 tog (a cool summer duvet) up to 13.5 tog or more for deep winter. It measures warmth, not weight or quality: a light down duvet and a heavier synthetic one can share the same tog.
Which tog should I use for each season?
As a general guide, summer duvets are around 2.25–4.5 tog, spring and autumn duvets around 7–10.5 tog, and winter duvets around 12–13.5 tog. Some people buy an all-season set: a light and a mid-weight duvet that pop together with press studs to make a warm winter tog. This calculator picks a band from the season or your room temperature and then adjusts for how warm you personally sleep.
How does room temperature change the recommendation?
The temperature your bedroom actually holds at night matters more than the calendar. A well-heated or well-insulated room stays warm enough that a lower tog is comfortable, while a cold room needs more. Set the season to 'auto' and enter your night-time bedroom temperature, and the calculator classifies it — warm (22 °C and up), mild (18–21 °C), or cool (below 18 °C) — and recommends accordingly.
Is the recommended tog exact?
No — it is comfort guidance based on common retail conventions, not a precise measurement. Bedding layers, mattress warmth, pyjamas, a partner's body heat, and simple preference all shift the ideal tog. Use the result as a sensible starting point, and if you run hot or cold, trust your own experience over the number.
Comfort guidance based on retail tog conventions, not a precise thermal measurement. Personal preference and bedding vary. Not professional advice.