A full size mattress, often called a double, measures 54 inches wide by 75 inches long (137 cm x 191 cm). This makes it 16 inches wider than a twin but six inches shorter than a queen. It suits single sleepers who want extra space, couples who sleep lightly, and taller individuals needing more length than a twin offers. Below, we break down key dimensions, compare other common sizes, and outline real-world fit considerations to help you choose confidently.
Standard Full Size Mattress Dimensions
Manufacturers in the United States typically specify these exact interior dimensions for a full size mattress. These measurements refer to the sleeping surface, not the frame or foundation.
- Width: 54 inches (137 cm)
- Length: 75 inches (191 cm)
- Typical depth (top to base): 8–12 inches (20–30 cm), depending on foam, innerspring, or hybrid design
Full Size in US Customary Units
In inches, a full size mattress is four and a half feet wide and six feet three inches long. This width provides each sleeper about 27 inches of personal space when sharing, making it noticeably roomier than a twin but more compact than a queen.
Full Size in Metric Units
Using the international standard, a full size mattress is 137 centimeters wide and 191 centimeters long. Metric measurements are useful when shopping overseas or comparing products that list dimensions in centimeters rather than inches.
Full Size vs Other Common Mattress Sizes
Understanding how full size compares to other options helps clarify when it is the right choice and when another size may be better.
| Size | Width (in) | Length (in) | Personal Space (in) | Best For |
|---|---|---|---|---|
| Twin | 38 | 75 | 38 | Children, teens, studio apartments, guest rooms |
| Full | 54 | 75 | 27 | Single sleepers, couples on a budget, taller users needing length |
| Queen | 60 | 80 | 30 | Most couples, taller people wanting more width and length |
| King | 76 | 80 | 38 | Larger bedrooms, couples who want maximum space |
Full Size Bedroom Fit and Layout
Room planning matters as much as mattress dimensions. A bedroom with at least 10 by 12 feet (3 x 3.6 m) generally allows comfortable access, dressing, and movement around a full size bed. Smaller rooms can still fit a full, but clearance on each side and at the foot of the bed is important for ventilation, cleaning, and ease of use.
- Minimum bedroom footprint: roughly 10 ft x 12 ft (3 m x 3.6 m)
- Clearance recommendations: 24–36 inches (60–90 cm) on at least one side for access; more if two people will use the bed regularly
- Consider door swing, windows, and furniture layout before finalizing placement
Full Size Mattress Types and Thickness
Width and length are consistent across types, but thickness and support vary. Common constructions include innerspring, memory foam, latex, and hybrid designs. Thickness typically ranges from 8 to 14 inches, influencing perceived comfort, edge support, and height.
- Budget-friendly options: 8–10 inches, often innerspring or basic foam
- Mid-range comfort: 11–13 inches with multiple foam layers or pocketed coils
- Premium feel: 14+ inches with advanced materials and reinforced edges
Full Size for Different Sleepers and Use Cases
This size works well for specific situations, even if it is not ideal for every bedroom or partnership.
- Single adults who want more space than a twin
- Guest rooms where occasional adults will sleep
- Teenagers transitioning from a twin to a larger mattress
- Couples on a tighter budget or with space constraints
- Individuals who are taller than average and need extra length without upgrading to a queen or king
Full Size Accessories and Compatibility
Check that bedding, foundations, and frames match the 54 by 75 inch profile. Standard full size fitted sheets, mattress protectors, and bed frames are widely available. Room for two sets of linens is generally needed if you plan to make the bed daily or rotate covers.
- Fitted sheet size: typically 54 x 75 inches with deep pocket options for thicker mattresses
- Protectors and encasements: same dimensions as the mattress surface
- Foundation options: slatted bases, solid platforms, or adjustable frames built for this size
Summary and Guidance
A full size mattress is 54 inches wide by 75 inches long, offering more width than a twin while staying six inches shorter than a queen. It is a practical choice for single sleepers, budget-conscious couples, taller users needing length, and guest rooms. Success depends on matching the mattress dimensions to your bedroom layout, sleeping habits, and long-term comfort preferences rather than choosing based on trend or impulse alone.