Twin XL sheet measurements and how to measure fitted sheet depth

Short answer: in common US sizing, Twin XL refers to a mattress about 38 x 80 inches. Some bedding charts list Twin XL at 39 x 80 inches. Treat those as the brand’s nominal fit dimensions, not the dimensions of a flat piece of fabric before sewing. Always confirm the fitted footprint and the pocket depth against your mattress height before buying Saatva bed sheet size guide, Casper sizing guide.

Twin XL measurements at a glance

• Mattress size: about 38 x 80 in (same width as Twin, 5 in longer) Peacock Alley: Twin vs Twin XL, Casper sizing guide.
• Example nominal fitted-sheet size listed by a brand: about 39 x 80 in for Twin XL Saatva bed sheet size guide.
• Pocket fit: use the maker’s stated mattress-height range and include the topper in your measurement. If a chart lists actual pocket depth, follow that brand’s allowance guidance; do not add the same allowance to an already stated maximum mattress height. One cited brand’s example ranges are standard 7-12 in, deep 13-17 in and extra-deep 18-25 in; these category names are not uniform across makers Saatva bed sheet size guide.

Measure and match your Twin XL fitted sheet

• Measure mattress length and width on the top surface: ~38 x 80 in for Twin XL
• Measure mattress depth on the side seam to seam, adding any topper height
• Pick the brand’s Twin XL size and confirm its stated fit includes your total mattress-plus-topper height

How to measure fitted sheet depth for a Twin XL

Strip the bed to the bare mattress. On a side panel, measure straight from the bottom seam to the top surface. If you use a protector or topper, add that thickness to get total depth. Distinguish a raw pocket-depth measurement from a stated maximum mattress height. Saatva offers a one-to-two-inch allowance as its guidance; check how your chosen brand describes fit rather than adding that allowance universally Saatva pocket-depth guidance.

Flat sheets and cases are not standardized

Flat-sheet and accessory sizes vary by brand, so check the product chart rather than assuming a single "standard." Examples:

• Some brands list Twin and Twin XL flat sheets the same, 66 x 96 in American Textile size chart, Casper sizing guide.
• Others publish a longer Twin XL flat, for example 72 x 114 in Saatva bed sheet size guide.
• Another example shows Twin XL flat around 75 x 112 in Peacock Alley bedding size basics.

Because these dimensions differ, treat the brand chart as the final word for flat sheets, duvet covers and pillowcases.

Worked example: choosing pocket depth

Your Twin XL mattress measures 12 in deep, and you use a 3 in foam topper. Total depth is 15 in. Choose the brand’s Twin XL sheet whose specified mattress-height capacity includes the combined 15 inches. Do not assume one extra inch guarantees fit or covers shrinkage; check that product’s fit and care guidance. The example uses the measured combined height; the product’s actual specification determines fit Saatva pocket-depth guidance.

Common pitfalls and quick fixes

• Buying Twin instead of Twin XL: both are 38 in wide, but Twin is only 75 in long, so a Twin fitted sheet will run short on a Twin XL Peacock Alley: Twin vs Twin XL.
• Ignoring mattress depth: most fit complaints are shallow pockets. Measure depth including any topper, then choose the right pocket tier Saatva pocket-depth guidance. For a deeper explainer, see our What bedsheet depth do I need?
• Assuming any Twin flat sheet will fit: flat dimensions vary; check the set’s chart before you buy American Textile size chart, Saatva bed sheet size guide.
• Sheets slipping off: after matching pocket depth, seat each fitted corner fully under the mattress, not just over the tip. More help in How to keep fitted sheets from slipping off a mattress.

Related explainer

Pocket size in plain English, with examples and fixes: What bedsheet depth do I need?

Quick pre-check before you add to cart

• Fitted label is the brand’s Twin XL size and its nominal fit matches your mattress
• Your combined mattress and topper height is within the maker’s stated fit range
• You reviewed the brand’s flat-sheet and pillowcase sizes for coverage

FAQ

Are Twin and Twin XL the same width?

Yes. Both are about 38 inches wide; Twin XL is 5 inches longer at about 80 inches Casper sizing guide, Peacock Alley: Twin vs Twin XL.

What counts as a deep pocket for fitted sheets?

As a guide, standard pockets fit about 7-12 in mattresses, deep 13-17 in, and extra-deep 18-25 in. Pick a pocket 1-2 in deeper than your measured mattress height Saatva pocket-depth guidance.

Buying for a split king?

A split king uses two Twin XL mattresses, so you need two Twin XL fitted sheets and typically a king top sheet Boll & Branch size guide.