The short answer: standard US mattresses are Twin (38 × 75 in), Twin XL (38 × 80 in), Full (54 × 75 in), Queen (60 × 80 in), King (76 × 80 in) and California King (72 × 84 in). The right size depends on who sleeps on it, how tall they are and how much floor space you have. Measure your room, your doorways and your stairs before you choose.
Picking a size is the first decision in any mattress search, and it’s the one that’s hardest to change later, because your sheets, frame and even your bedroom layout depend on it. This guide puts the standard dimensions side by side and walks through the practical questions that help you choose.
Standard mattress dimensions
| Size | Width × length (inches) | Often chosen for |
|---|---|---|
| Twin | 38 × 75 | Kids’ rooms, bunk beds, day beds |
| Twin XL | 38 × 80 | Taller single sleepers, smaller rooms, dorm-style beds |
| Full (Double) | 54 × 75 | Single adults who want more width, guest rooms |
| Queen | 60 × 80 | Couples, single adults who like to spread out |
| King | 76 × 80 | Couples who want the most width, families who share the bed |
| California King | 72 × 84 | Taller sleepers who want extra length |
These are the standard nominal sizes. Actual measurements can vary slightly from one manufacturer to another. Mattress height (thickness) isn’t part of the size name, but it matters for sheets and for how high the bed sits, so check it too, especially if you’re adding a pillow top.
How the sizes compare
A few comparisons make the chart easier to read:
- Twin vs. Twin XL: same width, but the XL is five inches longer. If a teenager or an adult will sleep on it, the extra length is worth considering.
- Full vs. Queen: a Queen is six inches wider and five inches longer than a Full. For two adults, a Full gives each person 27 inches of width, so many couples find it tight. For one adult, a Full can be plenty, and it leaves more floor space in a smaller room.
- Queen vs. King: a King adds sixteen inches of width over a Queen at the same length. That’s a lot of extra room for two people, but it also takes a lot more floor space and needs larger bedding.
- King vs. California King: a King is wider; a California King is longer and narrower. A standard King is the same footprint as two Twin XLs placed side by side.
Who is sleeping on it?
Start with the people, not the room. Ask a few simple questions:
- One sleeper or two? Two adults usually look at a Queen or larger. One adult may be happy with a Full, or may prefer a Queen for room to move.
- How tall is the tallest sleeper? If feet hang off the end of a 75-inch bed, look at the 80-inch sizes (Twin XL, Queen, King) or the 84-inch California King.
- Do kids or pets join you? If the bed regularly gets crowded in the morning, the extra width of a King can make a real difference.
- Do you move a lot at night? Restless sleepers and couples with different schedules often appreciate more width, so one person’s movement bothers the other less.
- Is it for a guest room? A bed that’s used a few nights a year can be sized for the room first. A Full or Queen covers most visitors.
Kids grow quickly, so it’s worth thinking a few years ahead. A Twin suits a young child, but a Twin XL or Full can carry a child into the teenage years. If you’re not sure where to start, our Mattress Match quiz asks these questions for you and passes your answers to our team before your fitting.
Will it fit your bedroom?
A mattress that fits the people can still crowd the room. Before you decide:
- Measure the room and sketch the layout. Mark the bed, nightstands, dressers, windows and doors. Make sure closet doors and drawers can open fully with the bed in place.
- Leave walking space. You should be able to walk comfortably around the sides and foot of the bed, especially in a room you use every day.
- Think about the frame, not just the mattress. Headboards, footboards and platform frames add to the footprint. An adjustable base also needs room to move.
- Tape it out. Painter’s tape on the floor at the size you’re considering shows quickly whether the room feels open or cramped.
If the room is tight, remember that length is often easier to give up than width: a California King is narrower than a King, and a Queen is a common compromise in a mid-sized room.
Check the path into the room
Large mattresses have to get through doorways, hallways and stairwells. Measure the narrowest point along the path, including tight turns at the top of stairs. Foundations and box springs don’t bend, so they’re usually the harder piece to move. Let us know about any tight spots when you book; with our free delivery and in-home setup, our team brings the mattress in and sets it up for you, and we’ll take your old mattress away at no charge.
Bedding and accessories
Changing size means changing more than the mattress. Plan for:
- Fitted and flat sheets in the new size, with pockets deep enough for the mattress height.
- A mattress protector sized to match.
- A frame, foundation or adjustable base that supports the new size.
- Pillows: two standard or queen pillows suit most Queen beds; King beds often use king-size pillows. Our guide on choosing a pillow for your sleep position can help.
Try the size before you buy
Numbers on a chart only tell you so much. Lying on a mattress in your own bedroom tells you far more about whether a Queen feels roomy enough or a King fits the space. That’s how we work: tell us your size, firmness and budget, and we bring 3-4 hand-picked mattresses to your home so you can test them where you’ll actually sleep. If you’re torn between two sizes, tell us when you book. You can see our mattress selection, then book your free at-home fitting.
