What Size Bed Do I Need? A UK Bed Sizes & Room Fit Guide

The UK has four bed sizes most people choose between: single (90 x 190cm), double (135 x 190cm), king (150 x 200cm) and super king (180 x 200cm).

Which one you need comes down to how many people are sleeping in it, how much floor space the room actually has once a wardrobe and walking space are accounted for, and whether you want storage underneath.

A double sleeps two at a squeeze, each getting about the width of a large cushion to themselves. A king gives each person roughly the width of a single bed.

Below is the full size chart, a practical look at how much room each size needs (including the government's own minimum bedroom standards), honest numbers on weight capacity, and whether underbed storage is worth the faff.

In this article

• What are the standard UK bed sizes?
• What size room do I need for each bed?
• Single, double or king: which is right for you?
• How much weight can a bed frame hold?
• Is underbed storage worth it?
• FAQ

What are the standard UK bed sizes?

UK sizing runs on its own scale, separate from the US "twin/full/queen" system. Here are the six sizes you'll come across, mattress dimensions first:

Those are mattress dimensions. The frame itself is bigger once you add the headboard, footboard and side rails: Opal Retail's own double frame measures 197.5cm long by 137.5cm wide overall, built around that standard 190 x 135cm mattress. Always check the frame's footprint against your room, not just the mattress size on the box.

What size room do I need for each bed?

Most size guides stop at "leave some space to walk round it," which isn't much use with a tape measure in hand. One genuinely official figure is worth knowing: the UK government's technical housing standards set a minimum new-build bedroom floor area of 7.5m² (at least 2.15m wide) for a single bedroom, and 11.5m² (at least 2.55m to 2.75m wide) for a double or twin bedroom.

That's a regulatory minimum for the whole room, not a guarantee the bed will feel comfortable in it.

For a more practical number, we worked out what each bed size needs once you allow 60cm of clearance down each side and at the foot of the bed, using real frame dimensions rather than just the mattress size:

Treat these as a sanity check, not gospel, and add more if a wardrobe needs to fit in the same room. One useful trick: the jump in frame width from double to king is only around 13cm, so a room that already fits a double comfortably will usually take a king too. It's the leap to super king that genuinely needs extra floor space.

Double bed frame

Double Bed Frame with Underbed Storage, Black

Fits a standard 135 x 190cm double mattress, with 272kg (42 stone) weight capacity and 32cm of underbed clearance.

From £73.99 Shop now →

Single, double or king: which is right for you?

Once the room can take more than one size, the choice stops being about floor space and starts being about who's sleeping in it.

• Solo sleeper, guest room or child's room: a single is the default, but a small double gives a growing teenager or taller adult more room without needing a double-sized bedroom.
• Couple who like sleeping close together: a double works, but at 135cm wide that's about 67.5cm each, less than a single bed per person. It's cosy by design, not by accident.
• Couple who want their own space: a king (150cm, about 75cm each) is the usual step up. A super king (180cm, 90cm each) gives each person the width of a single bed, which is why some couples call it "two single beds pushed together."

There's no right answer. Some couples move up a size and downsize again when they miss sleeping close together; others call it the best change they've made to how they sleep. Test a bed in person before committing, rather than guessing from the dimensions alone.

Single bed frame

Single Metal Bed Frame with Headboard & Footboard

Fits a standard 90 x 190cm single mattress, with 136kg (21 stone) weight capacity and 32cm of underbed clearance.

From £57.99 Shop now →

How much weight can a bed frame hold?

This comes down to how the frame is built, not just the size. A flimsy frame can feel wobbly or fail under ordinary bodyweight, usually a construction problem (slat spacing, a missing central support rail) rather than a size problem.

Opal Retail's single metal frame is rated to 136kg (21 stone); the double and king frames both hold 272kg (42 stone), thanks to a multi-leg design and a full slat base. Check the stated weight rating on whatever you're buying, and look for a central support rail on anything double-size or larger.

Is underbed storage worth it?

Two different things get sold as "underbed storage." An ottoman or divan bed has a sealed, hinged base you lift to store things inside, keeping dust out but needing a working gas-lift mechanism, which owners of heavier mattresses sometimes find harder to lift.

An open metal frame, like Opal Retail's, simply gives you clear floor space underneath, usually around 30 to 32cm, for boxes you slide in and out by hand. Less tidy to look at, but nothing to lift and nothing to maintain, which suits anything you get in and out of often.

King bed frame

King Size Metal Bed Frame with Underbed Storage

Fits a standard 150 x 200cm king mattress, with 272kg (42 stone) weight capacity and 31.6cm of underbed clearance.

From £70.99 Shop now →

Once you've settled on a size, our bedroom furniture buying guide covers fitting a wardrobe and storage around the bed, and our wardrobe sizing guide uses the same room-measuring approach if you're planning the whole room at once.

Frequently asked questions

Is a double bed really big enough for two adults?

It sleeps two, but at 135cm wide that's roughly 67.5cm of mattress each, narrower than a single bed. It's a cosy fit by design rather than a spacious one, so if you both want to stretch out without disturbing each other, a king is the comfortable step up.

Will a king or super king bed fit through my door or up my stairs?

The frame is rarely the problem, as most go up in pieces. It's the mattress, especially a super king, that can be too rigid and bulky to bend round a tight staircase. Measure your narrowest doorway and stairwell before ordering, and ask about a rolled or foam mattress delivery if space is tight.

What's the smallest room a double or king bed will actually fit in?

UK new-build regulations set 11.5m² as the minimum for a double or twin bedroom. In practice, allowing 60cm of walking space down each side and at the foot, a double needs roughly 2.6m x 2.6m and a king around 2.7m x 2.6m, using real frame dimensions rather than the mattress size. Add more if a wardrobe needs to fit too.

How much weight can a bed frame hold?

It depends on the frame, not just the bed size. Opal Retail's single frame holds 136kg (21 stone), and the double and king frames both hold 272kg (42 stone), thanks to a full slat base and multiple support legs rather than size alone.

Is underbed storage worth it?

If you want everything hidden behind a single lid and don't mind a bit of lifting, an ottoman or divan base is worth it. If you'd rather slide boxes straight in and out with nothing to maintain, an open frame with underbed clearance does the same job with less effort.

Should I buy a single or a small double for a child's room?

If the room can take it, a small double (120 x 190cm) gives a growing child noticeably more room than a single, without needing a full double-sized bedroom. It's a popular middle ground for box rooms a little bigger than the smallest in the house.