What Size Is a King Mattress in Inches? A Clear Guide to King Bed Dimensions
If you’re asking “What size is a king mattress in inches?”, you’re likely trying to confirm exact measurements, check if it will fit in your bedroom, or compare it to other mattress sizes. This guide answers those questions in a straightforward, FAQ-style format so you can plan with confidence.
What Size Is a King Mattress in Inches?
In the U.S., a standard king mattress typically measures:
- 76 inches wide
- 80 inches long
So when you see “What size is a king mattress in inches?”, the most common answer is:
This size is often called an “Eastern King” and is wider than a queen mattress, giving two sleepers more personal space.
Why Do King Mattress Dimensions Matter?
Knowing what size a king mattress is in inches is important for a few practical reasons:
- Room fit: You’ll want to be sure the bed fits comfortably in your bedroom with space to walk around and place furniture.
- Bedding compatibility: Sheets, mattress protectors, and toppers are sized to specific dimensions.
- Frame and base sizing: Bed frames and foundations must match the mattress size to provide proper support.
- Comfort for couples: The width of a king mattress allows many couples to spread out more compared to a queen.
A good rule of thumb is to measure your room before deciding on a king, especially in smaller spaces.
Are There Different Types of King Mattresses?
Yes. When people search “What size is a king mattress in inches?”, they’re often surprised to learn there is more than one kind of king. Here are the most common king-related sizes:
| Mattress Type | Dimensions (inches) | Key Difference |
|---|---|---|
| King (Eastern) | 76 x 80 | Standard king size in most U.S. bedrooms |
| California King | 72 x 84 | Narrower but longer than a standard king |
| Split King | Two 38 x 80 | Same total size as king, but in two pieces |
How Is a California King Different?
A California king is often confused with a standard king. In inches, it is:
- 72 inches wide
- 84 inches long
So a California king is 4 inches narrower but 4 inches longer than a standard king. Taller sleepers sometimes prefer the added length, while others choose a standard king for its extra width.
What Is a Split King?
A split king is essentially two twin XL mattresses side by side:
- Each side: 38 inches wide x 80 inches long
- Combined: 76 inches wide x 80 inches long (same total size as a standard king)
A split king can make moving the mattresses easier and allows each side to function separately on some adjustable bases.
How Much Space Do You Need for a King Mattress?
Beyond asking “What size is a king mattress in inches?”, it helps to think about the whole bedroom.
Many people find it useful to allow:
- At least 2–3 feet of clearance on each side of the bed
- Space at the foot of the bed for walking or storage furniture
- Room for nightstands on one or both sides, if desired
While there is no single “correct” room size, a king mattress tends to feel more comfortable in larger bedrooms where it doesn’t dominate the entire space.
Common Questions About King Mattress Dimensions
Will King Sheets Fit a California King?
No. Because the dimensions differ, standard king sheets (76" x 80") are not designed to fit a California king (72" x 84") properly. Each size typically needs correctly labeled bedding for a secure fit.
Is a King the Same as Two Twins?
A standard king is not the same as two regular twins. Two twin mattresses together measure about 76" x 75", which is shorter than a standard king. A split king is made from two twin XL mattresses (38" x 80"), which match a king’s length.
Do All King Mattresses Measure Exactly 76" x 80"?
Manufacturing and materials can sometimes lead to small variations of about an inch or so, but they are generally close enough that standard king bedding and frames still work as intended.
✔️ Quick Mattress Takeaways
Key points to understand about “What Size Is a King Mattress in Inches”
- Standard king size: About 76 inches wide by 80 inches long
- Category name: Often called an Eastern king in the U.S.
- Compared to queen: King is wider, offering more personal space for couples
- California king: About 72" x 84" — narrower but longer than a standard king
- Split king: Two 38" x 80" twin XL mattresses placed side by side
- Bedding note: Each king variation needs correctly sized sheets and accessories
- Room planning: Measure your space to ensure comfortable clearance around the bed
Understanding what size a king mattress is in inches—and how it compares to California king and split king options—helps you choose a mattress that fits both your bedroom and your sleeping preferences. With the exact dimensions in mind, it becomes much easier to plan your layout, select bedding, and feel confident in your decision.
