Twin Mattress Dimensions: Size in Inches, Feet & Thickness

A standard U.S. Twin mattress measures 38 inches wide by 75 inches long—about 3 feet 2 inches × 6 feet 3 inches, or 96.5 × 190.5 cm. Its footprint is 2,850 square inches, or about 19.8 square feet. A Twin XL keeps the same 38-inch width and adds 5 inches of length, measuring 38 × 80 inches (about 3 feet 2 inches × 6 feet 8 inches, or 96.5 × 203 cm).

These are mattress dimensions, not the outside measurements of the bed frame. Manufacturer specifications can vary slightly, so check the model label when a close fit matters.

Twin and Twin XL mattresses have the same nominal width, but Twin XL is 5 inches longer. A standard Twin is often used in a child’s room, bunk, guest room, or studio; Twin XL adds legroom for a taller single sleeper and is commonly used in dorm rooms. Those are common uses, not rules about who can sleep on each size.

Before buying, compare the mattress with the exact bed frame, foundation, fitted sheets, and room layout. Two Twin XL mattresses placed side by side match the nominal surface dimensions of a standard King mattress, but adjustable bases and frames must be designed for that arrangement.

For a room-level example, see our 10 × 12 bedroom layout guide.

There is no single standard Twin mattress thickness or weight. Both depend on the model's construction, foam or spring layers, and materials. For a clearly labeled example, Casper lists its “The One” mattress in Twin at 10 inches thick and 42 pounds; its Twin XL version is 10 inches thick and 43 pounds. Those are product-specific specifications, not averages for every Twin mattress.

When shopping for a bunk bed, trundle, or fitted sheet, use the mattress maker's stated height as well as width and length. A thick mattress can change guardrail coverage or affect how a fitted sheet fits, even when it is the correct Twin footprint. Check the bed maker's maximum mattress height if the bed has rails or a trundle.

“Short Twin,” “RV Twin,” and “narrow Twin” are not names for one universally fixed U.S. mattress dimension. Products using these labels can be designed for particular vehicles, bunks, or tight spaces, so their width and length may differ. Do not order bedding or a frame using the label alone; measure the mattress or check its exact model specifications.

A mattress sold as standard Twin is the familiar 38 × 75 inch size. If a fitted opening is smaller, compare the product's exact dimensions with the frame's inside width and length, then leave room for fabric covers and easy installation. The frame's exterior footprint is usually larger than the mattress itself.

Measure the mattress from edge to edge across its widest point, then from head to foot for its length. Measure thickness from the base to the highest point without compressing the mattress. Record width, length, and height separately; an online listing may display them in a different order.

For room planning, the mattress footprint alone is not the space the bed needs. Add the frame, walking clearance, drawers or a trundle, and room to make the bed. The mattress occupies about 19.8 square feet in a Twin size, but the actual sleeping setup takes more floor area. Our bedroom size guide compares room dimensions and layouts.