How Many Inches Is a King Size Mattress? Standard Dimensions Explained
If you’re asking “How many inches is a king size mattress?”, you’re likely measuring a bedroom, choosing bedding, or comparing sizes. This guide walks through standard king mattress dimensions in inches, why they matter, and how they compare to other common sizes.
What Are the Standard Dimensions of a King Size Mattress?
In most cases, a standard king size mattress measures:
- 76 inches wide
- 80 inches long
This is often called an “Eastern King.” When people ask How many inches is a king size mattress, this is usually the size they mean.
Is There a Height or Thickness Standard?
There is no universal standard thickness for king size mattresses. Height can vary widely, usually from about 8 inches to 14+ inches, depending on materials and construction.
Because thickness varies:
- Check the height if you have deep pocket sheets or a specific bed frame.
- Consider whether you want a lower profile (easier to get in and out of) or a taller, more substantial look.
Are There Different Types of King Size Mattresses?
Yes. When you search “How many inches is a king size mattress”, you might actually be seeing several related sizes. Here are the most common:
Standard King (Eastern King)
- 76" x 80"
- Widely used and easy to find bedding for.
- Good for couples who want extra width.
California King
- 72" wide x 84" long
- Slightly narrower but longer than a standard king.
- Often chosen by taller sleepers who want more legroom.
Split King
- Made from two Twin XL mattresses side by side.
- Each side: 38" x 80"
- Combined size: 76" x 80" (same sleeping surface area as a standard king).
- Often used with adjustable bases, so each side can move independently.
How Does a King Size Mattress Compare to Other Sizes?
To understand whether a king will fit your space, it helps to compare it to other common mattress sizes.
Simple Mattress Size Comparison (in Inches)
| Size | Width (in) | Length (in) |
|---|---|---|
| Twin | 38 | 75 |
| Twin XL | 38 | 80 |
| Full | 54 | 75 |
| Queen | 60 | 80 |
| King | 76 | 80 |
| Cal King | 72 | 84 |
A king mattress is:
- 16 inches wider than a queen (same length).
- Much wider than a full or twin, providing more personal space for each sleeper.
Why Do King Size Mattress Inches Matter?
Knowing exact king size mattress inches helps in several practical ways:
1. Room Size and Fit
A king mattress (76" x 80") can feel quite large in a small room. Before choosing one, consider:
- Clear walking paths on both sides.
- Space for nightstands, dressers, or other furniture.
- Doorways, stairways, and hallways the mattress must pass through.
2. Bedding and Accessories
Mattress dimensions affect:
- Sheet size (fitted sheets must match width, length, and often depth).
- Mattress protectors and toppers.
- Comforters and duvets (these are often a bit larger than the mattress surface for drape, but are still labeled by size).
If your mattress is especially thick, you may need deep-pocket king sheets.
3. Sleep Space for Couples
A standard king mattress gives each partner about the same width as a twin bed. Many couples choose king size for:
- Extra room to move without disturbing a partner.
- Space for a child or pet to occasionally join.
Frequently Asked Questions About King Mattress Measurements
Do all brands use the same king size dimensions?
Most follow the standard of 76" x 80", but small variations of 1–2 inches in width or length can occur due to manufacturing and materials. This is usually not noticeable in daily use but can matter with tightly fitted frames or custom bedding.
Will a king mattress fit on a queen bed frame?
Generally, no. A king mattress is both wider and sometimes configured differently than a queen frame. It’s best to use a frame designed specifically for king dimensions.
Is a king the biggest mattress size?
A standard king is one of the largest widely available sizes. However, some specialty or oversized sizes do exist beyond standard retail options. These can be larger in both width and length but are less common and may require custom bedding.
✔️ Quick Mattress Takeaways
Key points consumers should understand about “How Many Inches Is a King Size Mattress”
- Standard king size mattress:76 inches wide x 80 inches long
- California king:72 inches wide x 84 inches long (narrower, longer)
- Split king: two 38" x 80" mattresses forming a 76" x 80" surface
- Thickness is not standardized – commonly ranges from about 8" to 14"+
- A king is 16 inches wider than a queen, offering significantly more side-to-side space
- Always check room measurements, frame size, and sheet depth before choosing a king
- Small 1–2 inch variations between manufacturers are normal and usually not a problem for standard bedding
Understanding how many inches is a king size mattress helps you plan your bedroom layout, choose compatible bedding, and decide whether a standard king, California king, or split king best matches your space and preferences. With the basic dimensions in mind, it becomes much easier to make a confident, practical choice.
