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Most people know what size bed they have. Well, that is most people. Some still get hung up on the difference between a King and a Cal King. What really tricks people up is the depth of the mattress. Is it a pillow top? Do I need a deep or extra deep cover? In order to answer these questions, you've got to know how to measure a mattress for a mattress cover.
Standard Mattress Sizes
In the United States, the length and width of mattresses are standard. That's a good thing. To determine your standard size, use the following chart.
| Mattress Size by Name | Mattress Dimensions in Inches |
| King | 78 x 80 |
| California King | 72 x 84 |
| Queen | 60 x 80 |
| Full | 54 x 75 |
| Twin | 39 x 75 |
| Long Twin (Hospital Twin) | 39 x 80 |
Notice these sizes only refer to the length and width. Now where it gets tricky is the depth. A standard mattress is 8 to 9 inches deep. But who has a standard mattress these days?
How to Accurately Measure the Mattress Depth
Depth becomes important if you have a mattress that is larger or smaller than normal. That's because standard bedding is sewn to accommodate a standard mattress depth (no more than 9 inches).
Pillow top, plush top, and double pillow tops are where it starts to get tricky. The mattress is sewn with a top and bottom edge seam. If you were to measure the distance between these two seams to determine the depth, you would be wrong.
Take a look at this picture and you will see why.
If you measured the bottom of the mattress to the top seam you would get a measurement of 14". That would lead you to believe that a 15" mattress cover would fit your mattress. But, if you bought a 15" cover and had this mattress you would be in trouble. That's because this mattress is actually 16" deep.
To measure a mattress depth, you've had to measure the very top of the mattress. In this instance, we placed a small piece of wood on top of the mattress and then used a measuring tape to measure the distance between the bottom of the mattress and the bottom of the piece of wood.
That's 16 inches deep and a full 2 inches different from the measurement at the side of the mattress. If I ordered an organic cotton mattress encasement for this mattress I would order the King 18" deep. That's because 15" would be too small.
Tight is Not Good
When it comes to mattress covers, you don't want tight. Tight is not good. Tight makes it very hard to get the mattress cover on and off the mattress. The harder the chore, the less likely it will be performed. And you do need to perform this chore once or twice a year to wash the cover.
Tight also puts stress on the seams and zippers. That's also not good. Unstressed and laundered properly, a dust mite proof mattress cover should last for years. Stress on the seams and zippers just shortens the life of the cover.
Hope this information helps you measure a mattress for a mattress cover before you make a purchase. We want you to get the size you need without hassling with an exchange.