Mattress Sizes: Chart and Bed Dimensions
Pick a bed size to see its dimensions in inches, centimeters and feet, then enter your room to see which sizes fit with the clearance you want.
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This page lists US mattress sizes and checks which of them fit a room, free, in your browser. Choose a bed size, enter the two inside sides of your room in feet or meters, and set the clearance in inches. The tool shows whether that size fits, every size that fits, and the largest one by area. No sign-up is needed, and nothing is uploaded.
The size table works as a bed sizes chart, with each size in inches, centimeters, feet and inches, and square feet. Full size mattress dimensions, for example, are 54 × 75 in. The sizes come from two public guides, a mattress maker’s and a mattress retailer’s, and sizes vary slightly by maker, so check the label on the mattress you plan to buy. This page does not cover crib bed measurements; the crib page is linked below.
How to use the Mattress Size Chart
- Pick a “Bed size” from the list, or start from a preset: “Queen, 10 × 10 ft room”, “King, 12 × 12 ft room”, “Twin, 8 × 9 ft room” or “Full, 10 × 10 ft room”.
- Choose “Room measured in” feet or meters, then enter “Room side 1” and “Room side 2”. Measure inside wall to wall, without furniture.
- Enter the “Clearance around the bed (in)”. This is the walking space on each long side and at the foot, in inches. The default is 24 in. It is only a starting value that you choose, because no public size guide sets one. The Twin preset uses 18 in.
- Open “More options” if you want to change “People sleeping” between 1 person and 2 people. This sets the width per person in the table.
- Read the result. It gives the chosen size in inches, centimeters and square feet, and “In your room” says whether it fits.
- Check “Sizes that fit your room” and “Largest size that fits”, which is chosen by area.
- Scroll to the tables. One lists every size with the floor space needed, whether it fits and the width per person.
- Watch for warnings. They appear for a room side under 4 ft or over 100 ft, a clearance over 60 in, or when no size fits.
Change any number after loading a preset to match your own room. The calculation runs in your browser and nothing is stored.
What are the standard mattress sizes?
The table lists US sizes that two public guides agree on: a mattress maker’s size guide and a mattress retailer’s guide. Sizes are an industry convention rather than a regulation, and makers vary, so treat these as typical sizes from the named sources. Twin is 38 × 75 in, twin XL 38 × 80 in, full 54 × 75 in, full XL 54 × 80 in, queen 60 × 80 in, king 76 × 80 in and California king 72 × 84 in. A split king is two twin XL mattresses of 38 × 80 in side by side. Full XL and split king come from the retailer’s guide only, and the table says so.
Why does the twin mattress size vary between charts?
The mattress charts say the twin is 38 in wide, but a fitted-sheet chart from one maker lists it as 39 in. The twin row carries this note. Short queen and Olympic queen are not listed, because no source was found for them.
How does the room fit check work?
The check assumes the head of the bed sits against one wall, with the chosen clearance on both long sides and at the foot. Either side of the room can be the head wall. A size fits when its width plus 2 × clearance, and its length plus clearance, fit inside the room in one of the two orientations. For a queen in a 10 × 10 ft room (120 × 120 in) with 24 in clearance, the bed needs 108 × 104 in and fits. A king needs 124 × 104 in and does not fit. The California king needs 120 × 108 in and fits, so it is the largest size that fits by area.
What clearance should I enter?
You set the clearance. No public size guide gave a recommended value, so the 24 in default is only a starting point. A larger clearance makes it harder for a size to fit. In an 8 × 9 ft room (96 × 108 in) with 18 in clearance, as in the Twin preset, sizes up to queen fit. The queen needs 96 × 98 in, while the king and California king do not.
How is width per person worked out?
Width per person is the mattress width divided by 1 or 2 people. A queen shared by two people gives 60 ÷ 2 = 30 in each. This is arithmetic only. It does not say how comfortable a size will be.
Which size is the largest that fits?
The largest size is chosen by area, which is width × length in square inches. In a 12 × 12 ft room (144 × 144 in) with 24 in clearance, a king needs 124 × 104 in and fits, and every size in the chart fits. The king is the largest at 76 × 80 = 6,080 sq in, ahead of the California king at 72 × 84 = 6,048 sq in.
Sources (checked 15 October 2026): blog.saatva.com · mattressstoreslosangeles.com · saatva.com
Worked examples
| Input | Result |
|---|---|
| Queen, room 10 × 10 ft, 24 in clearance | largest fit: California king (6 sizes fit) |
| King, room 12 × 12 ft, 24 in clearance | largest fit: King (7 sizes fit) |
| Twin, room 8 × 9 ft, 18 in clearance | largest fit: Queen (5 sizes fit) |
| California king, room 3.5 × 4 m, 30 in clearance | largest fit: King (7 sizes fit) |
Calculated by the tool above; open it with the same values to see each step.
Frequently asked questions
What are the full size bed dimensions?
Full size bed dimensions are 54 × 75 in, which is 137.16 × 190.5 cm. The full XL is 54 × 80 in, and it comes from the retailer’s guide only.
What are the standard king size bed dimensions?
The standard king size bed dimensions are 76 × 80 in for a king mattress, or 193.04 × 203.2 cm. A California king is 72 × 84 in, so it is narrower but longer.
Is a twin mattress size always 38 × 75 in?
The mattress charts list 38 × 75 in, but sizes vary by maker. One fitted-sheet chart lists the twin as 39 in wide, so check the labels on your mattress and sheets.
What is the difference between a queen bed size and a full bed size?
A queen is 60 × 80 in and a full is 54 × 75 in. The queen is 6 in wider and 5 in longer.
What is a split king?
A split king is two twin XL mattresses of 38 × 80 in side by side, so it has the same footprint as a king, 76 × 80 in. It comes from the retailer’s guide only.
Does this page cover crib bed measurements?
No. This page does not list crib bed measurements. The crib mattress page covers them.
Does the tool store the room measurements I enter?
No. Nothing is stored or uploaded, and the calculation runs in your browser. The tool is free and needs no sign-up.
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