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The definitive answer on bed-sizes

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We get these questions a lot, so I am putting them here for all to see. The answers come by courtesy of the nice and helpful people at Sleep Country, Canada.

Twin ( Also called single) -: 37-1/2 by 74-1/2 inches

Twin long--------------------: 37-1/2 by 79-1/2 inches

Full ( Also called "double"): 53 by 74-1/2 inches

Full long----------------------: 53 by 79-1/2 inches

Queen------------------------: 60 by 79-1/2 inches

King---------------------------: 76 by 79-1/2 inches

All measurements are accurate to within 1-1/2 inches tolerance

Put differently, an ordinary Twin is between 73 and 76 inches long

I personally find the measurement rather more accurate than that.

Also note that two Twins moved together, make a King.

Underneath the matress is "the box", as it is called here. It obviously has the same lateral dimensions as the matress. The box lies on an expandable frame with coasters.


All the matresses in our house are (7 to 7-1/2) inches thick.

The boxes are typically (7-1/2 to 8) inches thick.

The flat area of the frame is (6-1/2 to 7) inches off the ground.

This means your total bed is (6-1/2 to7) + (7-1/2 to 8) + (7 to 7-1/2) = (21 to 22-1/2) inches off the ground. This allows you to calculate the size of duvets etc that you might want. The Canadian style is to have the duvet cover the top and fold over the sides a bit. The box then gets a bedskirt around the edge. I hate that and it is a misery to make such beds. The duvets we have for the Twin beds are 67 inches wide and 91 inches long.

The short and long bed versions use the same frame...the box just protrudes further at the bottom end of the bed. To go to Queen and King sizes, the expansion structure needs to have an extra leg in the middle to support the centre of the bed. I bought singles, but asked for the centre support expansion structures on the frames, just in case.

To get a better idea of matters, you can take a look online at the Sears selection.....and then decide where to buy. I bought all my stuff at Sleep Country. They absolutely consistently beat Sears on price. Now and then, Cosco have a superb deal on decent matresses. They are a wholesale membership operation, (a little like MAKRO) with an annual membership fee, that does not sell junk.

I hope all this helps to demystify things a little.

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Thanks Harry!

I think we'll bring our mattress with a specially made expandable frame from here, for the day our mattress goes to mattress heaven... ;)


Edited by Lala

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Thanks for the info, i was just about to post a topic asking about some of this stuff.



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South African bed sizes (for comparison)

Single bed mattress dimensions: 91cm x 188cm (35.827 X 74.015* inches)

Three quarter mattress dimensions: 107cm x 188cm (42.126 X 74.015* inches)

Double bed mattress dimensions: 137cm x 188cm (53.937 X 74.015* inches)

Queen bed mattress dimensions: 152cm x 188cm (59.843 X 74.015* inches

King size bed mattress dimensions: 183cm x 188cm (72.047 X 74.015* inches)

*Extra length 200cm (78.740 inches)

Edited by Merida
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You also need to look at the height of the mattress. This is called the "pocket size", when buying linen.

Edited by Nettie

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Thanks, Harry😊

Here is a full in-depth look at this ultimate guide with illustrations on South African bed sizes, which I've come across.

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Came here with a South African Queen size, with a frame of blackwood/yellow wood and loathe to get rid of it given the quality of the wood. However, obviously not in sync with North American sizes and when the time came to replace the mattress, what to do and so for years we did nothing. Then I discovered that the RV queen mattress is the same size as the South African queen and replacement was easy.

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