Tog rating is simply a measure of how well a duvet holds warmth: the higher the number, the warmer the duvet. It has nothing to do with weight or fabric weave, and everything to do with how much air the filling traps. That’s why a lightweight goose down duvet can outperform a heavier synthetic one at the same tog rating.
Tog Rating by Season: A Quick Reference
| Tog rating | Best for |
|---|---|
| 1.0–4.5 tog | Summer, hot sleepers, warm bedrooms |
| 7.5–10.5 tog | Spring and autumn, mild nights |
| 12–13.5 tog | Winter, cold bedrooms, unheated homes overnight |
| 15 tog+ | Very cold houses, or anyone who’s permanently cold |
If you’d rather not commit to one number year-round, a combination (or “all seasons”) duvet, two duvets that button together, lets you run a low tog on its own in summer and both togs combined for winter. It’s worth a look if you’ve been going back and forth on which single tog to buy.
How to Choose Between 10.5, 12 and 13.5 Tog
The honest answer is that it depends on three things more than the calendar: how warm your bedroom actually gets overnight, whether you run the heating while you sleep, and whether you personally run warm or cold. A few pointers:
- You heat your bedroom overnight, or live somewhere well insulated: 10.5 tog is often plenty, even in January.
- Your heating goes off at night and your room drops below about 16°C: 12 to 13.5 tog will make a noticeable difference.
- You’re a consistently cold sleeper, or your partner runs warmer than you do: 13.5 tog, or a combination duvet so you can each choose your own layer.
- You already sleep hot: don’t go above 10.5 to 12 tog just because it’s winter. A lighter duvet plus an extra blanket on the coldest nights is easier to regulate than an overly warm duvet.
For a closer look at how the filling itself affects warmth, not just the tog number, our guide to hollowfibre vs. microfibre duvets breaks down how different fills perform at the same tog rating, and our full duvet tog guide covers every tog band in more detail if you want the complete picture beyond just winter.
Down vs. Synthetic at the Same Tog Rating
Two duvets can share a tog rating and still feel completely different in bed. Down duvets (goose or duck) trap air more efficiently per gram of filling, so a 13.5 tog goose down duvet is noticeably lighter than a 13.5 tog hollowfibre duvet. Down is also more breathable, which is why down sleepers tend to report fewer of the “too hot, then too cold” swings that synthetic duvets can cause overnight.
The trade-off is care and price: down duvets typically cost more upfront and need more thoughtful washing and drying, while synthetic duvets are cheaper to replace and more machine-wash-friendly. If you’re weighing that decision, our piece on whether a goose down duvet is worth investing in goes through the trade-offs in full, and Hungarian goose down vs. regular goose down is worth a read if you’re deciding between down grades.
Getting the Right Size to Match Your Tog
A duvet that’s the wrong size for your bed undoes a lot of the benefit of getting the tog right, cold air gets in at the edges no matter how warm the filling is. If you’re due an upgrade for winter, it’s worth checking your sizing at the same time. See our duvet size guide if you’re not sure whether you need a king or super king, and our king vs. super king duvet comparison if you’re choosing between those two specifically.
When to Actually Switch to Your Winter Duvet
Tog rating only helps if you switch in time. Most people in the UK move to a warmer duvet sometime in October, once overnight temperatures settle below the mid-teens. We’ve covered the timing, and how to store whichever duvet you’re not using, in when to switch to a winter duvet.
Frequently Asked Questions
Is 13.5 tog too warm for winter?
Not for most people in an unheated bedroom. 13.5 tog is designed for the coldest UK winter nights. It can feel too warm if your room is well heated overnight or you naturally sleep hot, in which case 10.5 to 12 tog paired with a blanket for cold snaps is usually more comfortable.
What's the difference between 12 tog and 13.5 tog?
The difference is roughly 12.5% more filling and more trapped air, which translates to a noticeably warmer duvet rather than a subtle one. Most people find 12 tog suits a moderately heated bedroom, while 13.5 tog is better for a room that gets genuinely cold overnight.
Can I use a 13.5 tog duvet all year round?
You can, but you'll likely overheat in spring and summer. A 13.5 tog duvet is built specifically for cold weather. If you want one duvet for every season, a combination duvet that splits into a lighter layer and a warmer layer is a better fit than a single high-tog duvet worn year-round.
Does a higher tog rating mean a heavier duvet?
Not necessarily. Weight depends on the filling as much as the tog rating. A goose down duvet at 13.5 tog is typically lighter than a hollowfibre duvet at the same rating, because down traps more air per gram of filling.
What tog should I buy if my partner and I run different temperatures?
A combination or 'his and hers' duvet arrangement, two duvets of different togs that fasten together, lets each of you choose your own warmth without either compromising. It's a common solution for couples who disagree on winter bedding.
Shop winter-ready duvets or explore our full range of down duvets to find the right tog for your bedroom.
