Sheet sizing looks simple until you are standing in a store holding a package that says queen while quietly wondering whether it will fit the bed you already own. Two things make it confusing: sheet dimensions are not the same as mattress dimensions, and pocket depth is a separate measurement that packaging often buries in fine print.
This guide gives you the numbers, then tells you which sizes are genuinely interchangeable and which will waste your money.
Standard mattress sizes first
Every sheet size is derived from a mattress size, so start here. These are the US standards.
| Size | Mattress dimensions |
|---|---|
| Twin | 38 by 75 inches |
| Twin XL | 38 by 80 inches |
| Full (double) | 54 by 75 inches |
| Full XL | 54 by 80 inches |
| Queen | 60 by 80 inches |
| King | 76 by 80 inches |
| California king | 72 by 84 inches |
| Split king | Two twin XL mattresses, 38 by 80 inches each |
Fitted sheet sizes
A fitted sheet is cut to the mattress surface plus the depth of the sides, with elastic gathering the corners underneath. The labelled size matches the mattress, so a queen fitted sheet is cut for a 60 by 80 inch surface. What varies between brands is how deep the sides go.
| Fitted sheet size | Fits mattress surface | Common pocket depths |
|---|---|---|
| Twin | 38 by 75 in | 12 to 15 in standard, up to 18 in deep pocket |
| Twin XL | 38 by 80 in | 12 to 15 in standard, up to 18 in deep pocket |
| Full | 54 by 75 in | 12 to 15 in standard, up to 18 in deep pocket |
| Queen | 60 by 80 in | 12 to 16 in standard, up to 20 in extra deep |
| King | 76 by 80 in | 12 to 16 in standard, up to 20 in extra deep |
| California king | 72 by 84 in | 12 to 16 in standard, up to 20 in extra deep |
Flat sheet sizes
Flat sheets are cut much wider and longer than the mattress so there is enough overhang to tuck in on both sides and the foot. Sizes vary more between manufacturers than fitted sheets do, so treat these as typical rather than absolute.
| Flat sheet size | Typical dimensions |
|---|---|
| Twin | 66 by 96 in |
| Twin XL | 66 by 102 in |
| Full | 81 by 96 in |
| Queen | 90 by 102 in |
| King | 108 by 102 in |
| California king | 108 by 102 in |
Note that king and California king flat sheets are usually identical. Only the fitted sheet has to change between those two sizes.
Pocket depth is the number people forget
Pocket depth is how far the sides of a fitted sheet reach down before the elastic turns under. Get it wrong and the sheet either pops off a corner every night or bunches loosely in the middle.
Measure your mattress from the top surface to the bottom edge with a tape held flat against the side, and include anything permanently living under the sheet, such as a mattress protector or a topper. Then buy at least two inches more depth than you measured.
- Standard pocket, roughly 12 to 15 inches, fits most traditional innerspring and thinner foam mattresses.
- Deep pocket, roughly 16 to 18 inches, is the right choice for most modern pillow-top and hybrid mattresses.
- Extra deep pocket, 19 inches and up, is for very tall pillow-tops or a mattress plus a thick topper.
Modern mattresses have grown taller over the last two decades, which is why sheets that fit a bed bought in 2005 often will not fit its replacement. If you are adding a mattress topper, add its thickness to your measurement before you shop.
Which sheet sizes can you swap?
Some substitutions work, most do not.
- Full sheets on a queen bed: no. A full is six inches narrower and five inches shorter than a queen. The fitted sheet will not reach the corners, and the flat sheet leaves almost nothing to tuck. This is the single most common sheet-buying mistake.
- Queen sheets on a full bed: not really. The fitted sheet goes on but slides and wrinkles because the elastic has too much slack. The flat sheet is fine and simply hangs longer.
- King and California king: only the flat sheet swaps. A king fitted sheet is four inches wider and four inches shorter than a Cal king needs, so it will not sit correctly in either direction. Buy the fitted sheet in the right size.
- Twin sheets on a twin XL: no. The XL is five inches longer, which is exactly enough for the fitted sheet to pull off the top corners.
- Twin XL sheets on a split king: yes. A split king is two twin XL mattresses, so two twin XL fitted sheets are the correct answer. See our split king guide for how the rest of the bedding works.
- Full XL and Olympic queen: buy the exact size. These are uncommon and nothing else fits them properly.
Sheets for adjustable beds
An adjustable base does not change the sheet size, but it does change how hard the sheet works. Every time the head rises, the fabric is pulled toward the center of the bed, which is why standard-pocket sheets pop corners on adjustable bases. Buy deep pocket, and consider sheet straps or a fitted sheet with all-around elastic. We cover this in more detail in our guide to keeping sheets on an adjustable bed.
Fabric affects fit too
Cotton percale and linen shrink slightly on the first few washes, typically two to four percent, which manufacturers usually account for by cutting a little large. Jersey and bamboo have more stretch and are more forgiving of a mismatch in depth. If you are choosing between materials, our comparisons of percale and sateen and bamboo and cotton break down how each one behaves over time.
Frequently asked questions
Will full size sheets fit a queen bed?
No. A full mattress is 54 by 75 inches and a queen is 60 by 80 inches, so a full fitted sheet is short by six inches across and five inches lengthwise. It will not stay on the corners. Buy the queen size.
What are the measurements of a queen size bed sheet?
A queen fitted sheet is cut for a 60 by 80 inch mattress surface, with sides typically 12 to 16 inches deep. A queen flat sheet usually measures around 90 by 102 inches.
What are the dimensions of king size bed sheets?
A king fitted sheet covers a 76 by 80 inch mattress, and a king flat sheet is usually about 108 by 102 inches. That flat sheet also works on a California king, but the fitted sheet does not.
Will California king sheets fit a king size bed?
The flat sheet will, since both are typically cut the same. The fitted sheet will not: a California king is 72 by 84 inches and a king is 76 by 80 inches, so a Cal king fitted sheet is too narrow and too long for a king mattress.
What size is a twin bed sheet?
A twin fitted sheet fits a 38 by 75 inch mattress, and a twin flat sheet is typically around 66 by 96 inches. A twin XL needs its own size, since that mattress is five inches longer.
What size sheets fit a hospital bed?
Most home hospital beds use a 36 by 80 inch mattress, so twin XL sheets are the usual answer, though the fit is slightly loose across the width. Some manufacturers sell sheets cut specifically for hospital bed dimensions if you want a tighter fit.
Not sure what size your mattress actually is?
If you inherited the bed or bought it years ago, measure before you buy anything. Our mattress size comparison chart walks through every standard size and who each one suits, and our pillow size guide covers the matching pillowcases. If the measuring exercise reveals a mattress that has seen better days, take our sleep quiz or visit one of our five Los Angeles showrooms. We carry every standard size from twin to full and up, with same-day delivery ($100 upgrade, order by 4pm) on in-stock models.
