Serta's U.S. size chart lists Twin at 38 by 74.5 inches, Twin XL at 38 by 79.5, Full at 53 by 74.5, Queen at 60 by 79.5, King at 76 by 79.5, and California King at 72 by 83.5. Use these as Serta's published measurements, then check the exact mattress, frame and bedding dimensions because its conventional-size table allows a half-inch tolerance.
Use mattress labels to narrow the choice, then compare the exact mattress and frame dimensions. A size name is not a substitute for checking the product measurements, especially when a headboard, footboard or adjustable base changes the footprint.
Compare published dimensions
| Size | Serta chart, width by length |
|---|---|
| Twin | 38 by 74.5 in |
| Twin XL | 38 by 79.5 in |
| Full | 53 by 74.5 in |
| Queen | 60 by 79.5 in |
| King | 76 by 79.5 in |
| California King | 72 by 83.5 in |
These are Serta’s listed mattress dimensions. Its conventional bedding table references the ISPA dimension standard and gives finished mattress tolerances of plus or minus one half inch. Other makers may list different exact measurements, so compare the model page with the inside dimensions of your bed frame.
Match length and width to the room
Twin XL adds length compared with Twin; California King is longer and narrower than King in Serta’s chart. Consider the room shape, the people sharing the bed and the space needed to reach doors, drawers and closets. Mark the full mattress and frame footprint with painter’s tape before moving furniture.
A split King setup uses two Twin XL mattresses in Serta’s guide. Check that the adjustable base, fitted sheets and mattress protectors are made for the same split configuration. A split base can have different exterior dimensions from the mattresses it supports.
Check frame and bedding fit
Compare the mattress width and length with the frame’s interior size. Then measure the exterior footprint, including rails, headboard, footboard and any drawers. Check fitted-sheet pocket depth against the mattress height and any topper.
For another mattress decision, read the mattress firmness guide. Compare sheet thread count and weave and the rug size guide. Browse bedding and bath.
Sources
- Serta size and dimensions, conventional mattress dimensions and ISPA tolerances, checked November 5, 2026.
- Serta mattress size guide, model-family dimensions and split King guidance, checked November 5, 2026.
Common questions
What are the dimensions of a queen mattress?
Serta lists its Queen at 60 by 79.5 inches in its size chart and 60 by 80 inches in its conventional bedding table, which allows a half-inch tolerance. Check the exact model page before buying.
What is the difference between King and California King?
Serta lists King at 76 by 79.5 inches and California King at 72 by 83.5 inches. California King is narrower and longer in that manufacturer's chart.
Is a split king made from two Twin XL mattresses?
Two Twin XL mattresses are commonly used for a split King arrangement. Serta lists Twin XL at 38 by 79.5 inches; check the exact adjustable base and bedding dimensions before ordering.
How do I know which mattress size fits my room?
Measure the bed frame and room, mark the full footprint on the floor, then check walking space, drawers and the delivery path.