What Are The Dimensions Of a King Size Mattress? A Clear Guide to Width, Length, and Variations
If you’re wondering “What Are The Dimensions Of a King Size Mattress”, you’re usually trying to figure out two things: the exact measurements, and whether a king will realistically fit your bedroom and lifestyle. This FAQ-style guide walks through standard king mattress dimensions, common variations, and what to consider before choosing one.
What Are the Standard Dimensions of a King Size Mattress?
In most places that use inches, the standard king size mattress measures:
- 76 inches wide x 80 inches long
- Approximately 193 cm x 203 cm
This size is sometimes called an “Eastern King” and is the most common king mattress size.
A simple way to think about it: a king is basically two twin XL mattresses side by side, giving each sleeper space similar to a twin bed.
How Does a King Size Compare to Other Mattress Sizes?
Understanding what are the dimensions of a king size mattress is easier when you compare it to other common options.
| Mattress Size | Approx. Dimensions (W x L) | Typical Use |
|---|---|---|
| Full / Double | 54" x 75" | Single sleeper or cozy couple |
| Queen | 60" x 80" | Most common for couples |
| King | 76" x 80" | Couples wanting extra width |
| Cal King | 72" x 84" | Taller sleepers or narrow rooms |
📝 Key idea:
A king is wider than a queen by about 16 inches, but the same length. This extra width is what many couples notice most.
Are There Different Types of King Size Mattresses?
Yes. When people ask “What Are The Dimensions Of a King Size Mattress”, they often discover there’s more than one version. The two most common are:
Standard King (Eastern King)
- 76" x 80" (193 cm x 203 cm)
- Widest common mattress size for most bedrooms
- Often chosen by couples who want maximum personal space side by side
California King (Cal King)
- 72" x 84" (183 cm x 213 cm)
- Narrower but longer than a standard king
- Often preferred by very tall sleepers or for long, narrow rooms
💡 Remember: Bedding and bed frames are usually not interchangeable between a standard king and a California king, since their dimensions differ in both width and length.
How Much Room Do You Need for a King Size Mattress?
Knowing what are the dimensions of a king size mattress is only half the puzzle. The other half is making sure it fits comfortably in your room.
A common rule of thumb is to leave at least 2–3 feet of walking space on the sides and at the foot of the bed, when possible.
Before choosing a king:
- Measure the room length and width
- Consider space for nightstands, dressers, and doors
- Think about doorways, stairs, and hallways the mattress has to pass through
Many people find that a standard king works best in medium to large bedrooms, while a queen or smaller size may be easier to live with in compact rooms.
Do All King Mattresses Have Exactly the Same Dimensions?
Most standard king mattresses follow the 76" x 80" guideline, but small differences can happen:
- Some brands may vary by an inch or so
- Pillow-top or euro-top designs can feel slightly larger in height
- Foam mattresses may appear more flexible at the edges
Because of this, it’s usually wise to check the exact listed dimensions of any mattress and bed frame you’re considering, especially if your room is tight.
What Bedding Fits a King Size Mattress?
For a standard king mattress (76" x 80"):
- Look for “King” on fitted sheets, flat sheets, and comforters
- Make sure fitted sheets list a depth that matches your mattress height, especially if it’s extra thick or has a topper
- Duvets and comforters labeled “king” are generally designed to drape over the sides with some overhang
For a California king, bedding must be specifically labeled “Cal King” because of the different dimensions.
✔️ Quick Mattress Takeaways
Key points about “What Are The Dimensions Of a King Size Mattress”:
- Standard king size = 76" wide x 80" long (about 193 cm x 203 cm)
- Also known as an Eastern King
- California king is different: 72" x 84", narrower but longer
- A king offers significantly more width than a queen (about 16" more)
- Best suited to larger bedrooms with enough space to walk around the bed
- Always measure your room and doorways before committing to a king
- Check that bedding and frames match your exact king size (standard vs Cal King)
Understanding what are the dimensions of a king size mattress helps you plan your room, choose the right bedding, and decide whether this size truly fits your space and sleeping style. With clear measurements in mind, it’s easier to choose a mattress that feels comfortable not just to sleep on, but to live with every day.
