What’s The Size Of a King Size Mattress? Standard Dimensions & FAQs
If you’re asking “What’s The Size Of a King Size Mattress”, you’re usually trying to figure out whether it will fit your bedroom, your bed frame, or your sleeping needs. This guide explains the exact dimensions of a king mattress, how it compares to other sizes, and what to keep in mind before choosing one.
What Are the Standard Dimensions of a King Size Mattress?
In most cases, when people say “king size mattress,” they’re referring to the standard king (often called an Eastern king).
A standard king size mattress is typically:
➡️ 76 inches wide x 80 inches long
That’s about 6 feet 4 inches long and a bit over 6 feet wide, making it one of the widest standard mattress sizes available for home use.
These dimensions apply to most modern mattresses labeled “king” in regions that follow US sizing. However, exact measurements can vary slightly by manufacturer, so it’s common to see minor differences of an inch or so.
How Does a King Size Mattress Compare to a Queen?
If you’re debating whether you really need a king, it helps to compare it with a queen, which is a very common size.
| Mattress Size | Width (inches) | Length (inches) |
|---|---|---|
| Queen | 60" | 80" |
| King | 76" | 80" |
Key differences:
- A king is 16 inches wider than a queen.
- The length is the same (80 inches).
- For two adults, a king gives each person about the same width as a twin mattress.
If your main concern is more personal space side-to-side, a king can be a noticeable upgrade from a queen.
Are There Different Types of King Size Mattresses?
When people search “What’s The Size Of a King Size Mattress,” they sometimes discover that “king” is not just one single size. There are a few common king variations:
Standard King (Eastern King)
- 76" x 80"
- Widely available and most common when you see “king” without any extra terms.
California King
- 72" x 84"
- Narrower but longer than a standard king.
- Often preferred by taller sleepers who want extra legroom.
Split King
- Two separate mattresses, each 38" x 80", placed side by side.
- Pushed together, they equal the size of a standard king (76" x 80").
- Often used with adjustable bases or when partners prefer different mattress feels.
Knowing which “king” you’re looking at helps avoid surprises with sheets, bases, and room layout.
How Much Space Do You Need for a King Size Mattress?
A common follow-up to “What’s The Size Of a King Size Mattress” is whether it will actually fit in the room.
A standard king (76" x 80") usually works best in:
- Primary bedrooms or larger rooms
- Spaces where you can comfortably walk around the bed on at least two or three sides
Many people aim to leave at least 24–30 inches of open space on each side and at the foot of the bed for walking and furniture. While room sizes vary widely, a king mattress often feels most practical in rooms roughly around:
- 12' x 12' or larger, depending on how much furniture you have
The bed frame, headboard, and footboard can add several inches, so it’s helpful to measure both the mattress dimensions and the frame you plan to use.
Will Standard Bedding Fit a King Size Mattress?
Most bedding labeled “king” is designed to fit a standard king (76" x 80") mattress. However, there are a few details to watch:
- Fitted sheets: Check the pocket depth to match your mattress thickness.
- Comforters and duvets: Often sized to drape over the sides; some brands run larger or smaller.
- California king vs king: These usually require different sheet sets, even though they’re both “king” types.
When in doubt, match bedding to the exact mattress type (standard king vs California king vs split king).
✔️ Quick Mattress Takeaways
Key points consumers should understand about “What’s The Size Of a King Size Mattress”
- Standard king size mattress: usually 76" wide x 80" long.
- A king is 16" wider than a queen but the same length.
- Common king variations include standard king, California king (72" x 84"), and split king (two 38" x 80" mattresses).
- A king mattress generally suits larger bedrooms, often around 12' x 12' or more, depending on furniture.
- Always consider frame size, walking space, and doorways when planning for a king bed.
- Bedding labeled “king” typically fits a standard king, while California king bedding is sized differently.
- Small dimension differences between brands are normal, so it can be helpful to check the specific measurements for any mattress you’re considering.
Understanding what’s the size of a king size mattress helps you plan your room layout, choose compatible bedding, and decide whether the added width is worth it for your space and sleeping preferences. With the dimensions in mind, it’s easier to see how a king mattress will fit into your home and daily routine.
