US mattress sizes
These are the standard sizes in Sealy’s guide:
| Size | Width × length |
|---|---|
| Twin | 38 × 75 in |
| Twin XL | 38 × 80 in |
| Full (double) | 54 × 75 in |
| Queen | 60 × 80 in |
| King | 76 × 80 in |
| California king | 72 × 84 in |
Two twin XL mattresses side by side make a split king, also 76 × 80 in. Individual models can differ slightly from these standard sizes, and depth varies from model to model, so measure your own mattress if the fit matters.
For quilts and covers
The mattress top is only the start. Decide how far you want the quilt to hang down each side (the drop), then:
- Width = mattress width + 2 × drop
- Length = mattress length + drop at the foot, plus extra if you want it to tuck under the pillows
A queen quilt with a 12 inch drop on both sides and the foot is 60 + 24 = 84 inches wide and 80 + 12 = 92 inches long. Measure the mattress depth first: the drop needs to be at least that deep to cover the sides.
The batting size calculator and quilt backing calculator take it from there.