Home & Auto Calculators
Mattresses that claim to be queens, tires that speak in three number codes, rooms that looked bigger before the furniture arrived: sizing questions do not stop at your wardrobe. These tools decode the labels and check the fit before you buy.
- Bed Size ChartUS mattress dimensions compared, plus a will-it-fit check for your bedroom.
- Comforter Size ChartBed covering dimensions by size and type, plus the drop that decides the fit.
- Curtain Size CalculatorCurtain width from fullness, plus panel length by style and rod height.
- Paper Size ChartA0 to A10, Letter, Legal, Tabloid: exact dimensions and the folding logic.
- Rug Size CalculatorRug size from your room or your bed, snapped to a size you can buy.
- Tire Size CalculatorDecode 225/45R17 into real inches, or compare two sizes and see the speedo error.
- TV Size CalculatorDiagonal to true width and height, or couch distance to the size you should buy.
Sizing questions do not stop at your wardrobe
The things in your house have sizes too, and they are labelled just as loosely. A queen mattress is a genuine standard. A tire size is three numbers in three different units stuck together. A television is measured on a diagonal nobody can see, and paper sizes come in two families that do not convert to each other.
What these four tools share is that the number on the label is not the number you need. You need the space it takes up, the space you have, and whether one fits in the other.
US mattress dimensions
Mattress sizes are one of the few things on this site that really are standardised. These are the US dimensions our bed size chart uses, in inches.
| Size | Width | Length |
|---|---|---|
| Twin | 38 | 75 |
| Twin XL | 38 | 80 |
| Full | 54 | 75 |
| Queen | 60 | 80 |
| King | 76 | 80 |
| California King | 72 | 84 |
Two of these surprise people. A King is wider than a California King, not narrower: the California trades four inches of width for four inches of length, which makes it the better bed for a tall sleeper and the worse one for a couple who want room. And a Full is only 16 inches wider than a Twin, which is eight inches each for two adults, less shoulder room than a single sleeper gets in a Twin.
The dimension people forget is the room, not the bed. Leave at least 24 inches to walk around a bed and 30 inches to do it comfortably. A queen in a 10 by 10 room leaves 30 inches a side and 40 at the foot, which works. A king in the same room leaves 22 a side, which does not.
Reading a tire sidewall
A tire marked 225/45R17 is telling you three separate things in three separate units, which is why it reads like a code. The 225 is the tread width in millimetres. The 45 is the aspect ratio, a percentage: the sidewall height is 45 percent of the width, not 45 of anything absolute. The 17 is the wheel diameter in inches.
Because the middle number is a ratio, changing the width silently changes the height. Going from a 225 to a 245 at the same aspect ratio makes the sidewall taller as well as the tread wider, and the overall diameter grows.
That matters because your speedometer is calibrated to a diameter. The usual guidance is to stay within 3 percent of the original overall diameter, beyond which the speedometer error becomes large enough to notice and, in some places, large enough to matter legally.
Screen size, and the distance that goes with it
A television is measured diagonally, so the number tells you almost nothing about how much wall it needs. A 16:9 screen's width is its diagonal multiplied by about 0.87, and its height by about 0.49. A 65 inch set is therefore roughly 57 inches wide, which is the number that decides whether it fits the unit you own.
Distance is the other half. At 4K you can sit between one and one and a half times the diagonal away, because the pixels are small enough that you stop being able to see them. At 1080p you want one and a half to two and a half times, or the picture structure becomes visible. The higher resolution does not make the picture better from across the room, it lets you sit closer.
Two paper families that do not meet
The A series is defined by a ratio. Every A size has the same proportions, and halving one gives you the next: A4 folded is A5, A5 folded is A6. That is why scaling a document between them never crops anything.
US Letter and Legal come from a different tradition and share none of that. Letter is fractionally wider and shorter than A4, which is why a document laid out for one prints with drifting margins on the other, and why Legal is not a member of any ratio family at all. There is no conversion between the two systems, only a choice of which one to design for.
Frequently asked questions
How big is a queen size bed?
A queen mattress is 60 inches wide by 80 inches long. That is 6 inches wider and 5 inches longer than a full, and 16 inches narrower than a king at the same length.
Is a California King bigger than a King?
Not in area, and not in width. A King is 76 by 80 inches while a California King is 72 by 84, so the California trades 4 inches of width for 4 inches of length. It is the better bed for a tall sleeper and the worse one for a couple who want shoulder room.
How much space do I need around a bed?
At least 24 inches to walk past comfortably and 30 inches to feel unrestricted. A queen in a 10 by 10 room leaves 30 inches each side and 40 at the foot, which works. A king in the same room leaves 22 inches a side, which does not.
What do the numbers on a tire mean?
In 225/45R17 the 225 is tread width in millimetres, the 45 is the aspect ratio as a percentage of that width, and the 17 is wheel diameter in inches. Because the middle number is a ratio rather than a fixed height, changing the width also changes the sidewall height.
How wide is a 65 inch TV?
About 57 inches. A 16:9 screen's width is roughly 0.87 times its diagonal and its height roughly 0.49 times, so the advertised number is never the measurement you need for a wall or a media unit.
Is A4 the same as US Letter?
No, and they do not convert. A4 is part of a ratio family where folding one size gives you the next, while Letter comes from a different tradition entirely. Letter is slightly wider and shorter than A4, which is why a document laid out for one prints with drifting margins on the other.
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