Mattress protector sizes
Match the bed's width and length, then check how thick a mattress the pocket will fit.
Short answer: buy a protector labeled for your mattress size, then check the pocket depth. One maker lists twin 39 × 75 in, twin XL 39 × 80 in, full 54 × 75 in, queen 60 × 80 in, king 76 × 80 in and California king 72 × 84 in, and says all sizes fit a mattress up to 14 in thick.[1 · Nov 12, 2026] Another maker says its protectors fit any mattress up to 14 in deep.2 That first maker's twin and twin XL are listed 1 in wider than the usual 38 in mattress width,[3 · Nov 12, 2026] so read the dimensions on the listing.
One maker's protector dimensions
| Size | This maker's protector (in)[1 · Nov 12, 2026] | Usual mattress (in)[3 · Nov 12, 2026] |
|---|---|---|
| Twin | 39 × 75 in | 38 × 75 in |
| Twin XL | 39 × 80 in | 38 × 80 in |
| Full | 54 × 75 in | 54 × 75 in |
| Queen | 60 × 80 in | 60 × 80 in |
| King | 76 × 80 in | 76 × 80 in |
| California king | 72 × 84 in | 72 × 84 in |
Both makers we checked say their protectors fit mattresses up to 14 in thick.1,2 If you use a topper, measure the mattress and topper together. The same 14 in mark shows up for sheets: a sleep-research guide says standard sheet sets might not fit mattresses taller than 14 in, and it lists standard pockets at about 7 to 14 in and extra-deep pockets at 16 to 24 in.[4 · Nov 12, 2026]
Once the protector is on, you still need sheets that match the height. See sheet sizes and pocket depth and the mattress size chart.
Questions people ask
What size mattress protector do I need?
Buy the size that matches your mattress name, then check the listed width, length and pocket depth. One maker lists protectors in twin through California king and says they fit mattresses up to 14 in thick.
Will a protector fit a thick mattress?
Two makers we checked say their protectors fit mattresses up to 14 in deep. If your mattress plus topper is taller than that, look for a deeper pocket and confirm the listing.
Are twin protectors always 38 in wide?
No. The usual twin mattress is 38 × 75 in, but one maker lists its twin protector at 39 × 75 in. Check the listed dimensions.
Affiliate links: if you buy through a link in this box we may earn a commission, at no extra cost to you. It does not change the sizes or sources on this page. How we handle affiliate links.
Sources: 1. Helix Sleep help, What are the dimensions of the Mattress Protector?. 2. 
Layla Sleep help, Will the Layla Mattress Protector fit my mattress?. 3. Sleep Foundation, Mattress sizes and dimensions guide. 4. Sleep Foundation, Bed sheet sizes. Checked Nov 12, 2026. Trademarks belong to their owners; figures are restated in our own words and tables, not reproduced.