King size sheet dimensions include a 76″ × 80″ fitted sheet (sometimes listed as 78″ × 80″), a 102″–110″ × 102″–112″ flat sheet, and 20″ × 40″ king pillowcases. Measuring your mattress depth before buying ensures the fitted sheet stays secure and fits properly.
This guide breaks down every king size sheet dimension you need, from fitted to flat to pillowcase, so your next set fits the first time.
What Are King Size Sheet Dimensions?
King Fitted Sheet Dimensions
The king fitted sheet is cut to fit the top of a 76-inch by 80-inch mattress. Most brands list it as 76″ x 80″, though some round up to 78″ x 80″ to allow a small manufacturing tolerance. Both numbers describe the same sheet for the same bed.
Two sheets can share the exact same 76″ x 80″ label and still fit completely differently once you put them on.
King Flat Sheet Dimensions
A king flat sheet is the loose top layer that lies over you and tucks under the mattress. It needs to be bigger than the mattress itself to hang over both sides and the foot of the bed. Sizes vary by brand, but most fall between 102″ x 102″ and 110″ x 112″.
King Pillowcase Dimensions
King pillowcases measure 20″ x 40″. King is the only size with its own longer case, built for the longer king pillow.
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King Mattress Depth and Deep Pocket Sheet Sizes
Standard vs. Deep Pocket vs. Extra Deep Pocket
- Standard pocket: fits mattresses up to about 14 inches deep
- Deep pocket: fits mattresses between 15 and 17 inches deep
- Extra deep pocket: fits mattresses 18 inches deep or more
A memory foam mattress alone often runs 10 to 14 inches. Add a mattress topper or a pillow-top layer, and the total height can climb past 18 inches fast. That’s why a sheet that fit your old mattress may not fit a new one, even if both are labeled king.
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King Size Sheets vs. Other Bed Sizes
King vs. California King Sheet Dimensions
A California king mattress measures 72 inches wide by 84 inches long, four inches narrower and four inches longer than a standard king. That shape difference means the sheets are not interchangeable in either direction.
A king fitted sheet on a California king bed will be too wide and four inches too short, leaving the foot corner exposed. A California king sheet on a standard king bed will pull too tight lengthwise while leaving slack on the sides. If you’re not sure which bed you own, measuring both the width and the length settles it immediately.
King vs. Queen Sheet Dimensions
A queen mattress measures 60 inches wide by 80 inches long, the same length as a king but 16 inches narrower. That width gap is the reason queen and king sheets cost differently; more width means more fabric.
Flat sheets are the one exception worth knowing. Because a flat sheet has extra overhang built in on every size, a full or queen flat sheet can sometimes work as a top layer on a smaller frame, even though the fitted sheet cannot cross sizes at all.
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Other King Size Sheet Dimensions You Should Know
Eastern King vs. King Size Sheets
Eastern king and king size describe the exact same 76″ x 80″ mattress. The Eastern label exists only to separate it from California king, and you’ll mostly see it used by hotels and retailers that stock both sizes side by side.
If a listing says Eastern king, standard king sheets are the correct purchase.
Split King Sheet Dimensions
A split king setup uses two separate Twin XL mattresses, each measuring 39″ x 80″, placed side by side to fill a king-sized frame. That means you need two Twin XL fitted sheets rather than one king fitted sheet.
The flat sheet and pillowcases, however, stay at full king size, since those pieces cover the bed as a whole once both mattresses are together.
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FAQs About King Size Sheet Dimensions
What size are king size bed sheets?
A king fitted sheet measures 76″ x 80″ (sometimes listed as 78″ x 80″), the flat sheet runs roughly 102″ to 110″ wide by 102″ to 112″ long depending on brand, and king pillowcases measure 20″ x 40″.
Can I use queen sheets on a king bed?
No, not the fitted sheet. A queen fitted sheet is 16 inches too narrow for a king mattress. A queen flat sheet can sometimes work as a loose top layer, but it won’t offer full coverage.
Will king sheets fit a California king?
No. A California king mattress is 4 inches narrower and 4 inches longer than a standard king, so a king fitted sheet will not reach the corners at the foot of a California king bed.
What size pillowcases come with king sheets?
King sheet sets include king-sized pillowcases at 20″ x 40″, built for the longer king pillow rather than the standard 20″ x 30″ case used on every smaller bed size.
How do I know what depth of sheet I need?
Measure straight down the side of your mattress, including any topper or protector. Up to 14 inches calls for a standard pocket, 15 to 17 inches needs deep pocket, and 18 inches or more requires extra deep pocket.
James Walker is a content researcher and writer specializing in dimensions, measurements, size comparisons, and conversion topics. He creates clear, practical, and easy-to-understand guides that help readers visualize and understand real-world measurements.