What Size Is a Double Size Mattress? Mattress Dimensions Explained

If you’re asking “What Size Is a Double Size Mattress”, you’re usually trying to figure out whether it will fit your room, your bed frame, or two sleepers comfortably. The term “double” can also be confusing because it overlaps with “full” in many regions.

This FAQ-style guide breaks down double mattress dimensions, how they compare to other sizes, and what to consider before choosing one.

What Size Is a Double Size Mattress?

In many mattress guides, a double mattress is the same as a full-size mattress.

The typical dimensions of a double size mattress are:

• 54 inches wide x 75 inches long
• Approx. 137 cm x 191 cm

These measurements can vary slightly between manufacturers, but 54" x 75" is widely treated as the standard.

A helpful way to think of it:
A double is 15 inches wider than a twin, but the same length as a standard twin mattress.

Why Is It Called a “Double” If It’s Not Very Big?

The name “double” originally referred to the fact that it was wider than a single (twin) mattress, so it could fit two sleepers more easily than a twin.

However, by modern standards, many people find that a double (full) mattress:

• Feels roomy for one adult
• Feels cozy or tight for two adults, especially if both prefer extra personal space

This is one of the main misconceptions behind the question “What Size Is a Double Size Mattress”—the name suggests a large two-person bed, but in practice it’s often considered a step up from a twin, not a substitute for a queen.

How Does a Double Mattress Compare to Other Mattress Sizes?

Here’s a simple comparison to put double mattress dimensions in perspective:

Key differences:

• Compared with a twin, a double gives you extra width for stretching out.
• Compared with a queen, a double is narrower and shorter, which can matter for both comfort and room layout.

Is a Double Mattress the Same as a Full Mattress?

In many regions, yes.
When people ask “What Size Is a Double Size Mattress”, they’re often unknowingly asking about a full-size mattress.

• “Double” and “full” usually refer to 54" x 75"
• Some retailers may use only one term; others list both together (e.g., “double/full”)

If you are shopping or measuring, use the actual dimensions rather than assuming based on the name.

Who Is a Double Size Mattress Best For?

A double mattress is commonly chosen for:

• Single adults who want more room than a twin allows
• Teenagers transitioning from a childhood bed
• Guest rooms where space is limited
• Smaller bedrooms or studio apartments

Many couples find a double manageable for short-term use, but those who like more space often gravitate toward queen or king sizes.

Will a Double Mattress Fit My Bed Frame and Bedding?

When considering What Size Is a Double Size Mattress in real-world terms, frame and bedding compatibility are important:

• Bed frame: Look for frames labeled “double” or “full” and confirm the inner dimensions match around 54" x 75".
• Mattress foundation or base: Slatted bases, box foundations, and platform beds are usually clearly labeled for size.
• Sheets and bedding: Choose full/double sheets and comforters. Queen bedding will generally be too large and loose; twin bedding will be too small.

A small variation of an inch or so in mattress size from one brand to another is common and usually still works with standard frames and bedding.

How Much Space Does a Double Mattress Need in a Room?

To decide if a double is right for your room, consider:

• The mattress itself is 54" x 75", but the bed frame adds extra inches.
• It’s often recommended to leave walking space around the bed so the room feels comfortable to move in.

A double mattress is frequently used in:

• Smaller primary bedrooms
• Guest bedrooms that double as an office
• Rooms where a queen might feel too dominant

✔️ Quick Mattress Takeaways

Key points to remember about “What Size Is a Double Size Mattress”:

• Standard size: About 54" wide x 75" long (137 cm x 191 cm)
• Same as: Commonly the same as a full-size mattress
• Compared to a twin:15 inches wider, same length
• Compared to a queen:6 inches narrower and typically 5 inches shorter
• Best suited for:
  • Single adults or teens
  • Guest rooms and smaller bedrooms
• Fit check: Use the exact dimensions to confirm compatibility with your frame, room, and bedding

Understanding What Size Is a Double Size Mattress helps you plan your space, choose the right bedding, and set realistic expectations for comfort—especially if more than one person might be using the bed.