A full size mattress, also called a double, measures 54 inches wide by 75 inches long. That’s 137 by 191 centimeters. It’s one of the most misunderstood sizes on the market: “full” and “double” mean the same thing, and despite the name, a full is not built for two adults to sleep comfortably long-term. This 2026 guide gives you the exact numbers, how the size fits a real room, and how it stacks up against a queen and a twin.
Full size mattress dimensions in inches and cm
Standard full dimensions are consistent across US brands, though a few thickness and “full XL” variations exist. Here’s how the full compares to the sizes around it:
| Size | Inches (W x L) | Centimeters (W x L) | Sleeps |
|---|---|---|---|
| Twin | 38 x 75 | 97 x 191 | 1 (child or adult) |
| Twin XL | 38 x 80 | 97 x 203 | 1 (tall adult) |
| Full (Double) | 54 x 75 | 137 x 191 | 1 adult, or 2 in a pinch |
| Full XL | 54 x 80 | 137 x 203 | 1 tall adult |
| Queen | 60 x 80 | 152 x 203 | 2 adults |
| King | 76 x 80 | 193 x 203 | 2 adults, roomy |
The key takeaway: a full gives each of two people just 27 inches of width, narrower than a crib mattress each. It’s 6 inches narrower and 5 inches shorter than a queen. For the full picture across every size, see our bed sizes and dimensions guide.
How a full mattress fits a room
A full mattress needs a footprint of about 54 by 75 inches for the mattress alone, and a frame adds a few inches on each side. To walk around the bed and open a door comfortably, plan for a room of at least 10 by 10 feet (about 3 by 3 meters). A full will physically fit in a 9-by-9-foot room, but you’ll lose easy access on one side.
- Small bedrooms and guest rooms: a full is often the sweet spot, giving a single sleeper real room to spread out without dominating the floor.
- Under a loft or in a bunk: some bunks take a full on the bottom. Confirm the frame is rated for it and check our twin over full bunk beds guide.
- Two adults: possible but tight. If you share the bed nightly, a queen is worth the extra 6 inches.
Full vs. queen vs. twin: which to choose
Each size solves a different problem, and the right pick depends on who sleeps there and how much room you have.
- Twin (38 x 75): best for kids, bunks, and the smallest rooms. Too narrow for most adults who want to move around at night.
- Full (54 x 75): the most spacious size for a single adult and a solid choice for guest rooms. Its main weakness is length: at 75 inches, sleepers over 6 feet will hang off the end, which is why Full XL and Twin XL exist.
- Queen (60 x 80): the default for couples and the most popular size in the US. It adds width and, crucially, 5 inches of length over a full.
Who a full size mattress suits
A full is the right call if you’re a solo adult who likes room to sprawl, you’re furnishing a guest room, or you’re fitting a bedroom that can’t comfortably take a queen. It’s also a practical step up from a twin for a growing teen, as long as they’re under about 6 feet tall. It’s the wrong call if two adults share the bed every night, or if the sleeper is tall enough to need those extra inches of length.
Bedding and shopping notes
Buy sheets and frames labeled “full” or “double”; they’re interchangeable. Watch for “full XL,” which needs its own longer sheets. When you’re ready to shop the mattress itself, our budget roundups are a good starting point: see the best mattresses under $500 for full-size value picks. If you sleep hot, also check the best cooling mattresses.
In short, a full size mattress is 54 by 75 inches, ideal for one adult with room to spare, and best avoided if you need length or nightly space for two. Match the size to the sleeper and the room, and the full earns its long-standing popularity.
Marcus Reed
Marcus Reed is TalkBeds' Senior Mattress Tester and the person behind most of the hands-on verdicts you'll read on the site. Over more than eight years reviewing beds, he has personally tested 200-plus mattresses across every major category, from budget boxed foam… Full profile & sources →
