If you’ve ever stood in a bedroom trying to work out whether a king will actually fit, or wondered why a “small double” exists at all, you’re not alone. UK bed sizes have their own logic, and the names don’t always make it obvious.
Here’s a breakdown of what each size actually measures, and how to figure out which one works for your room. Find out exactly what you need to know below.
UK Bed Size Dimensions at a Glance
Before getting into the details, here are the standard UK sizes in both metric and imperial:
- Small single: 75 cm x 190 cm (2ft 6in x 6ft 3in)
- Single: 90 cm x 190 cm (3ft x 6ft 3in)
- Small double: 120 cm x 190 cm (4ft x 6ft 3in)
- Double: 135 cm x 190 cm (4ft 6in x 6ft 3in)
- King: 150 cm x 200 cm (5ft x 6ft 6in)
- Super king: 180 cm x 200 cm (6ft x 6ft 6in)
These are mattress dimensions. The bed frame will add a few centimetres on each side, so always measure based on the frame size when planning your room layout.
Small Double vs Double: A 15 cm Difference That Matters
The small double, also called a 4ft, is one of the more misunderstood sizes. At 120 cm wide, it’s technically wide enough for two adults, but it’ll be a squeeze. It’s a better fit for a solo sleeper who wants more room than a single but has a smaller bedroom to work with.
A standard double at 135 cm is the more comfortable option for couples, though it’s still modest by modern standards. If you’re both average build and you sleep fairly still, it works well. It’s also the most common size for guest rooms, since it handles one or two people without dominating the space.
Worth noting: both the small double and double share the same length, 190 cm. If you or your partner is over 6ft, you’ll want to look at king or super king, which both run to 200 cm.
King vs Super King: How Much Space Do You Actually Need?
A king size bed at 150 cm wide gives a couple noticeably more room than a double, roughly 7.5 cm more per person, which sounds small but makes a real difference night to night. The extra 10 cm in length (200 cm vs 190 cm) is the other key change, making king the go-to for taller sleepers.
If you’re shopping for a bed with under-bed storage, it’s worth looking at ottoman beds at this size. Retailers like Beds on Legs stock them across all standard UK sizes, and a king footprint gives you considerably more storage capacity than a double, which is useful if wardrobe space is limited.
A super king at 180 cm wide is a serious statement. You’ll need a room that can absorb it without feeling cramped. Most interior designers suggest a minimum room width of around 3.6 metres to use a super king comfortably. It’s the closest the UK market gets to a US or European king, and it’s increasingly popular for main bedrooms where space allows.
What About Mattress Lengths? US vs UK Sizing
This catches people out when buying online. A US queen mattress is 152 cm x 203 cm, which sounds close to a UK king, but the proportions don’t match standard UK bed frames. If you’re buying a frame and mattress separately, make sure both are sized to the same standard. Mixing up a US-sized mattress with a UK frame, or vice versa, will leave you with gaps or an overhang.
How to Choose the Right Size for Your Room
There’s no universal answer, but a few practical checks will narrow it down quickly:
- Measure your room first. Allow at least 60–70 cm on each side of the bed for walking room, and more if you need drawer or ottoman access.
- Factor in the frame, not just the mattress. Bed frames typically add 5–10 cm on each side.
- Think about length, not just width. If you’re over 6ft, a king or super king is worth the extra cost, a double will feel short after a while.
- Don’t buy down in size to save money. A cramped bed affects sleep quality every night. If the room can genuinely fit a king, it’s usually worth stretching the budget.
The Important Takeaway
All in all, the choice comes down to three things: room dimensions, how many people are sleeping in the bed, and how tall they are. A small double is a practical solo option. A double works for most couples in a mid-sized room. A king is the upgrade that tends to pay for itself in better sleep, and a super king is for those with the room to pull it off properly.
If you’re also weighing up bed types alongside size, it’s worth deciding on storage needs early. The size of the bed affects how much you can store underneath it, which can make a meaningful difference in a smaller home.
