What Are the Measurements of a King Size Bed?

The Measurements in Full

A UK king size bed measures 150cm wide by 200cm long, which is 5ft by 6ft 6in. That is the mattress measurement, and it is the figure every UK retailer uses when a bed is described as king size. The frame sits outside those numbers, so the space a king bed actually occupies in a room is larger: typically 155cm to 175cm wide and 205cm to 215cm long, depending on the style of the headboard and the thickness of the side rails.

Those two sets of numbers are the whole story, and confusing them is the single most common reason a bed arrives and will not sit where it was planned to go. Mattress measurements matter for bedding and toppers. External frame measurements matter for the room.

Breaking Down the External Size

An upholstered frame adds the most, because padding wraps the outside of the timber structure. On a fabric king, expect roughly 10cm to 12cm of extra width across the pair of side rails, and a similar amount at the foot if there is a padded surround. Slim metal frames add the least, often only 4cm or 5cm in total width.

Length is affected mainly by the headboard. A flat panel headboard adds around 5cm. A deep buttoned or winged headboard can add 15cm or more, and that projection sits between the wall and the top of the mattress, pushing the whole bed further into the room than the plan allowed.

Ottoman and storage frames deserve a separate note. Their external measurements are usually similar to a standard frame, but they need clearance to open. A side lifting ottoman needs free floor space along one edge, and an end lifting ottoman needs around 80cm at the foot for the gas lift to travel. If you are weighing up a storage base, our range of ottomans UK sale is the place to compare lift directions before committing to a layout.

How Much Room a King Needs

Work from the room, not the bed. Measure the wall the headboard will sit against, then measure from that wall to the opposite wall or to the nearest obstruction. A king bed works comfortably in a room from about 305cm by 335cm, which is 10ft by 11ft, and it will physically fit in something smaller if you accept a single approach side.

The clearances to protect are these. Allow 60cm to 70cm on each side you want to walk down, and remember that a bedside cabinet reduces that gap. Allow 70cm at the foot if there is nothing there, and 90cm if a wardrobe door opens onto that space. A hinged wardrobe door needs its full arc, and a king bed placed 60cm away will stop it at halfway.

Doors and radiators are the details that catch people out. A door that opens inwards needs its swing kept clear, and a bed rail across a radiator will trap heat under the mattress and dry out the timber over time. If floor space around the frame is tight, a sliding door wardrobe removes the swing entirely, and the modern sliding wardrobes UK range shows how much that can free up in a room where a king is already the priority.

Bedding Measurements for a King

A king duvet is 225cm by 220cm. Read that carefully, because it is wider than it is long, and it is the only common UK duvet size where that is true. The extra width is what gives a 150cm mattress enough overhang on both sides.

Fitted sheets for a king are cut to 150cm by 200cm, but the depth of the pocket is the part worth checking. Standard fitted sheets allow for a mattress around 25cm deep. Deeper mattresses, particularly pocket sprung models with a pillow top, run to 30cm or more, and a standard sheet will pull off the corners every night.

Pillows are standard UK size, 50cm by 75cm, and two of them across a 150cm king leaves 50cm of bare mattress. King size pillows at 50cm by 90cm fill the width better and give a tidier finish, though standard pillows in a pair remain the practical choice for most sleepers.

Mattress Depth and the Finished Height

The measurement nobody records is vertical. Frame height plus mattress depth gives the finished height of the bed, and comfortable sitting height for most adults falls between 55cm and 65cm from floor to the top of the mattress.

A low frame at 25cm paired with a 30cm mattress lands at 55cm, which is fine. A tall divan style base at 40cm paired with the same mattress reaches 70cm, which is high enough to feel like a climb. Buy the frame and the mattress as a pair where you can, and if you are replacing only the mattress, check its depth against the one you are removing before ordering. Our mattresses UK sale listings state the depth of each model, which makes that comparison straightforward.

Confirming the Measurements Before You Order

Two checks take five minutes and prevent almost every delivery problem. First, mark the external frame measurements on the floor with masking tape, then walk the route you would take to get in and out of bed and to open every door and drawer in the room.

Second, measure the delivery route. King frames arrive flat packed in long boxes, and the side rails are the awkward pieces at over 200cm. Measure the narrowest point of the route, usually a stair turn, a landing corner or a doorway at the top of the stairs, and check the diagonal clearance rather than the straight width. Where the answer is genuinely tight, an upholstered frame that arrives as separate panels is easier to carry than a solid timber frame with fixed rails.

It also helps to plan the surrounding pieces at the same time. Two bedside cabinets either side of a king add 80cm to 100cm of total width to the arrangement, and if that pushes the layout past the wall, a single cabinet on the approach side is the cleaner answer. You can compare narrow and wide options across the modern bedside cabinets UK sale range.

Choosing a King Frame to Suit the Measurements

Once the numbers are settled, the frame style decides how the bed feels in the room. Upholstered frames read as soft and take up visual space as well as physical space, which suits a larger room. Wooden frames with slim rails and an open base underneath keep sightlines low and make a mid size room feel less full.

Metal frames are the lightest visually and the narrowest externally, which makes them useful where every centimetre counts. High gloss frames reflect light and work well in rooms with a single window. If you want to see how the same 150cm by 200cm mattress size looks in a slimmer build, the king size wooden beds UK sale selection is a useful place to compare rail depths and headboard profiles.

Whatever you choose, keep the mattress measurement and the frame measurement separate in your notes. Bedding is bought to 150cm by 200cm. The room is planned to the external size. Get both right and a king bed sits in a UK bedroom without any of the compromises people usually associate with upsizing.

We stock beds, mattresses and bedroom storage in every UK size across a range of materials and finishes, and you can browse the full collection at Furniture in Fashion, with free delivery to most UK mainland postcodes.

Where the Measurements Usually Go Wrong

Almost every problem with a king bed traces back to one of four measurement errors, and each is easy to avoid once named.

Using the mattress size to plan the room. The 150cm figure tells you nothing about how much wall the bed needs. Always plan from the external frame width.

Ignoring the headboard projection. A deep buttoned headboard can push the whole bed 15cm further into the room than the plan allowed, which comes straight out of the walkway at the foot.

Forgetting the swing and the lift. A wardrobe door needs its full arc, a chest of drawers needs its drawer extension, and an ottoman base needs its lift clearance. These are all measurements even though none of them appear on a floor plan.

Measuring the doorway but not the stair turn. The turn is nearly always the tighter of the two, and it is the diagonal clearance that matters rather than the width.

Recording the Measurements You Will Need Later

Keep a short note of five figures when the bed goes in, because you will want them again. The external frame width and length, the mattress depth, the finished height from floor to the top of the mattress, and the clear gap on each side of the bed.

Those five numbers cover almost every future decision. Mattress depth tells you which fitted sheets to reorder. Finished height tells you what bedside cabinet height works. The clear side gaps tell you whether a bench, a rug or an additional cabinet will fit without blocking the walkway.

Rug sizing is a good example of why this is worth doing. A rug under a king bed should extend at least 60cm beyond the frame on the sides you walk down, which on a 165cm external frame means a rug of around 285cm width to look correct. Without the frame measurement written down, that calculation gets guessed.

Frequently Asked Questions

What are the exact measurements of a UK king size bed?

The mattress is 150cm wide by 200cm long, or 5ft by 6ft 6in. The frame around it usually measures 155cm to 175cm wide and 205cm to 215cm long depending on the headboard and rail design.

Is a UK king the same as a US king?

No. A US king is wider at 193cm and shorter at 203cm, and a US queen at 152cm by 203cm is closer to a UK king in width. Bedding bought abroad will not fit a UK king mattress properly.

What size duvet fits a king size bed?

A king duvet measures 225cm by 220cm, wider than it is long. That extra width gives even overhang on both sides of a 150cm mattress.

What is the smallest room a king bed will fit in?

Around 305cm by 335cm, or 10ft by 11ft, allows walking space on both sides and at the foot. Smaller rooms can take a king if you accept access from one side only.

How deep can a mattress be on a king frame?

Most king frames take mattresses from 20cm to 32cm deep. Check the finished height of frame plus mattress stays between 55cm and 65cm, and check your fitted sheets allow for the depth you choose.