Twin Bed Dimensions

Updated November 11, 2026 · By Serge, King Size Bed

Twin bed dimensions start with the standard US twin mattress: 38 x 75 inches (97 x 191 cm), about 3 feet 2 inches wide and 6 feet 3 inches long. A twin XL is the same width and 5 inches longer, 38 x 80 inches. The frame adds to that: across 66 twin bed frames listed by a US online furniture store, the median outside size was 42.1 x 80.4 inches.

Twin and twin XL mattress dimensions

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The voluntary guideline of the International Sleep Products Association lists the twin at 38 x 74.5 inches and the twin XL at 38 x 79.5 inches, with half an inch of tolerance. Labels round them to 75 and 80. Thickness is not part of the size. Our twin XL dimensions guide compares the two sizes, with the price gap between them.

In the US, "single" and "twin" are the same bed. A UK single is a different size, so check the inches when you compare.

Twin bed frame dimensions

We read the listed outside dimensions of 66 twin bed models sold by a US online furniture store (September 2026; bunk beds, loft beds, daybeds and trundles left out):

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Most twin frames hug the mattress: 54 of the 66 (82%) were 43 inches wide or less. The longest ones are sleigh beds, storage beds and beds with a bookcase headboard. The median listed height was 52 inches, mostly the headboard; the middle half ranged from 48.4 to 53.8 inches.

Twin vs twin XL vs full

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The twin XL only changes the length. It is the one to pick for a tall teenager: 75 inches is 6 feet 3 inches, and a sleeper near that height, plus a pillow, runs out of bed.

A full is 16 inches wider than a twin and the same length. In the store's listings, 65 models came in both twin and full: the full frame was 15 inches wider at the median, and 58 of the 65 had exactly the same length. Our double bed dimensions guide goes through the full in detail, and our bed sizes chart lists every US size.

A continental single is 90 x 200 cm, or 35.4 x 78.7 in, 2.6 in narrower than a twin XL. The other sizes are in our guide to European bed sizes.

Do two twin beds make a king?

Two twins side by side measure 76 x 75 inches: as wide as a king, but 5 inches too short, so a king mattress or king sheets will not fit them properly.

Two twin XL mattresses side by side measure 76 x 80 inches, exactly a king. That is what a split king is, and it fits a regular king frame. Our split king bed guide explains the sheets and frames it needs.

How big a room do you need for a twin bed?

A twin is often pushed against a wall, which changes the math. We use 24 inches as the smallest comfortable walkway; that is our rule of thumb, not an official standard.

With the median twin frame of 42.1 x 80.4 inches:

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What size rug for a twin bed?

With the median 42.1-inch frame centered on the rug:

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For a bed pushed into a corner, a single runner or a 4 x 6 rug on the open side does the job. Moving up to a king? Our guide gives the rug size for a king bed.

Sheets and bedding for a twin

• Sheets: twin sheets fit a twin. A twin XL needs twin XL fitted sheets, which are 5 inches longer. Flat sheets vary, so check the length on the package before using a twin one on a twin XL.
• Pocket depth: a fitted sheet is cut for the top plus the mattress thickness, so match it to the height of your mattress.
• Comforters: sizes vary by brand. Many are sold as "twin/twin XL"; read the measurements before you buy.

Pocket depth follows the mattress, which raises the question of how thick is a mattress today: half of the 223 US models we read were 10 to 14 inches.

Twin and single bed sizes in other countries

Outside North America a twin is called a single, and it is a different bed. Against a US twin of 38 x 75 inches:

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A European 90 x 200 cm mattress is nearly as long as a twin XL but 2.6 inches narrower, so twin XL sheets sit loose across it. A UK single dropped into a US twin frame leaves a gap of about 2.5 inches along one side.

Twin mattresses on bunk beds and trundles

Bunk beds, loft beds and trundles often take a twin mattress, but the frame sets how thick it may be. US safety rules for bunk beds require the top of each guardrail to stand at least 5 inches above the top of the mattress, which is why bunk bed makers state a maximum mattress thickness. A thick pillow-top can bring the sleeper up level with the rail, so check that figure before you buy the mattress.

A trundle has to roll under the main bed, so look for the maximum mattress height in its listing as well. None of these frames are in our figures above: bunk, loft, daybed and trundle listings were left out.

Moving up to a bigger bed

A twin is the bed for one child, one teenager or a guest room. For two people, the smallest size worth considering is a queen, and a king gives each sleeper as much width as a whole twin: 38 inches. See our king size bed dimensions guide and our king size bed frames, each listed with its outside size.

We only sell two sizes: the king size bed, as wide as two twin XL mattresses side by side, and the California king.

Frame figures: listed outside dimensions and heights of 66 twin bed models, and of the full and queen versions listed alongside them, sold by a US online furniture store, as listed on September 29, 2026 (one figure per distinct model; bunk, loft, daybed and trundle listings left out). Mattress sizes: the dimensional guideline of the International Sleep Products Association.

Next sizes up: full vs queen bed and queen size bed dimensions.

Between two twin beds, one table can serve both; the standard nightstand height, about 24 inches, suits a typical mattress top.