What Is The Size Of a King Size Mattress? Exact Dimensions & Key Questions Answered
If you’re asking “What Is The Size Of a King Size Mattress”, you’re likely trying to figure out whether it will fit your bedroom, your bed frame, or your lifestyle. This guide walks through standard king mattress dimensions, how they compare to other sizes, and what to consider before choosing one.
What Is The Size Of a King Size Mattress in Inches and Centimeters?
In most regions that use U.S. sizing, a standard king size mattress measures:
- 76 inches wide x 80 inches long
- Approximately 193 cm wide x 203 cm long
This is often called an “Eastern King” and is the most common type of king mattress found in many mattress stores and online.
The key takeaway:
A king mattress is about the width of two twin mattresses placed side by side, but slightly shorter than a California king.
Why Does the Size of a King Mattress Matter?
Understanding What Is The Size Of a King Size Mattress helps with:
- Room planning: Ensuring the bed fits comfortably with space to walk around.
- Bedding and accessories: Choosing the right size bed frame, foundation, and sheets.
- Sleeping comfort: Assessing how much personal space each sleeper will have.
A king mattress is typically chosen by:
- Couples who want more elbow room than a queen offers.
- People who share the bed with children or pets.
- Sleepers who prefer a more spacious feel.
How Does a King Mattress Compare to Other Mattress Sizes?
Here’s a simple size comparison chart for common mattress sizes:
| Mattress Size | Approx. Dimensions (W x L) | Notes |
|---|---|---|
| Twin | 38" x 75" (97 x 191 cm) | Single sleeper, kids or small rooms |
| Full/Double | 54" x 75" (137 x 191 cm) | One adult or cozy two-person use |
| Queen | 60" x 80" (152 x 203 cm) | Most common for couples |
| King | 76" x 80" (193 x 203 cm) | Extra width for couples |
| California King | 72" x 84" (183 x 213 cm) | Narrower but longer than king |
Key difference:
- King: wider (76") and slightly shorter (80")
- California King: narrower (72") but longer (84")
If height and legroom matter more than width, some people lean toward a California king. If side-to-side space is the priority, a standard king often makes more sense.
How Much Space Does Each Person Get on a King Size Mattress?
On a standard king:
- The total width is 76 inches.
- For two sleepers, that’s about 38 inches of space each—similar to each person having a twin bed.
This can feel more spacious than a queen, where two sleepers share 60 inches in total.
Many couples choose a king when they:
- Feel crowded on a queen.
- Have different sleep positions and movements during the night.
- Share the bed with a child or pet and want more room to spread out.
Will a King Size Mattress Fit in My Bedroom?
Knowing What Is The Size Of a King Size Mattress is only part of the equation. You also need to consider your room’s layout.
A common guideline is to leave at least 2–3 feet of clearance on each side and at the foot of the bed for easy movement.
✅ Quick room-planning tips:
- Measure your floor space before choosing a king.
- Account for bedside tables, dressers, or benches.
- Consider doorways, hallways, stairs, and elevators for delivery and setup.
- Visualize the bed with a frame and possible headboard, which add extra length and width.
In smaller rooms, a king mattress can dominate the space and make it feel tight. In larger rooms, it often creates a balanced focal point.
Are There Different Types of King Size Mattresses?
Yes, several variations exist beyond the standard king:
- Standard/Eastern King – 76" x 80"; most common.
- California King – 72" x 84"; longer, slightly narrower.
- Split King – Two pieces, each 38" x 80", placed side by side to create a king size.
- Less common regional kings – Some regions may have slight variations in dimensions or naming.
The split king is especially popular with adjustable bases because each side can move independently while still forming a full king sleeping surface.
What Bedding Do I Need for a King Mattress?
Once you know What Is The Size Of a King Size Mattress, matching bedding becomes simpler:
- King fitted sheet: Designed for 76" x 80".
- King flat sheet and duvet/comforter: Sized to drape over a king mattress.
- Pillows: Many people use standard, queen, or king pillows based on preference.
It’s important to choose bedding labeled specifically “king”, not “queen” or “California king,” since dimensions differ.
✔️ Quick Mattress Takeaways
Key points to understand about “What Is The Size Of a King Size Mattress”:
- Standard king dimensions: About 76" x 80" (193 x 203 cm).
- Space per sleeper: Roughly 38" of width each for two people.
- Best for: Couples wanting extra space, families with kids or pets in the bed, and larger bedrooms.
- Room fit: Works best when you can leave comfortable walking space around the bed.
- Not the same as California king: King is wider and shorter; California king is narrower and longer.
- Bedding: Look for king-sized sheets and duvets to match these dimensions.
Understanding the exact size of a king size mattress helps you plan your bedroom layout, choose compatible bedding, and decide whether the extra width is right for how you sleep.
