Sizes
5 sizes, and the one each is mistaken for
There is no federal rule fixing how big a mattress is. What is federally regulated about a mattress is how it behaves in a fire. The dimensions below are what retailers in the United States commonly list, and the reason that matters is the third column: pocket depth is where the absence of a standard turns into a fitted sheet that will not stay on.
| Size | Commonly listed dimensions | Depths stated in this catalog | Items here in this size | Most often confused with |
|---|---|---|---|---|
| Twin | 38 × 75 in | 14 to 15 in2 of 5 listings state one | 5 | Twin XL, Single |
| Twin XL | 38 × 80 in | 15 in2 of 4 listings state one | 4 | Twin, Two Twin XLs sold as a split king, A dorm listing that just says extra long |
| Full | 54 × 75 in | 14 in1 of 3 listings state one | 3 | Double, Queen, Full XL |
| Queen | 60 × 80 in | 14 to 21 in17 of 30 listings state one | 30 | Olympic queen, The pillow size called queen, Full |
| King | 76 × 80 in | 18 in1 of 4 listings state one | 4 | California king, Split king |
Each size has its own page with the corner drawn to scale, the full depth table for that size, and the specific reasons it gets mixed up with its neighbors. If you already know your mattress and what is going on top of it, Pocket Check does the arithmetic instead.