How to Measure Your Mattress

Measuring your mattress is an important part of making sure that the encasing will properly fit your bed. Most mattresses follow similar sizes for Width (W) and Length (L) that relate to conventional bedding sizes, such as:

  • Twin: 39″ x 75″
  • Long Twin: 39″ x 80″
  • Full: 54″ x 75″
  • Queen: 60″ x 80″
  • King: 78″ x 80″
  • CA King: 73″ x 84″

Mattress Height (H) = Encasing Depth

Although the overall sizes listed above may be fairly typical, the biggest difference will be in the height of the mattress.  Many mattresses are now made with a pillow top, a foam top or other bedding toppers that add to the overall height of the mattress.  It’s important to measure the full height of the mattress, including these toppers, since the encasing must zip around the whole area.

Please note that the encasing’s depth must fit the height of the mattress plus the toppers.

Allergy Partners encasings are made to suit typical mattress heights and are available in 4 depths: 9″ depth, 12″ depth, 15″ depth and 18″ depth (for select sizes and brands).

To measure your mattress’ height, follow these steps:

  • Place a hard edge ruler at the lower seam of the mattress.
  • Measure to the highest point of the mattress.
  • Include the full height of the pillow top, foam topper, mattress pad (if pad is placed inside encasing, as recommended) or other mattress topper.
  • Order your encasing to fit the full height of the mattress and topper.  If in doubt, order a deeper size to ensure fit.
  • Make sure that you don’t press on the top of the mattress while measuring, which can reduce the height measurement.
  • Our best advice:  Measure Twice, and Make the Right Choice Once!
  • Any questions?  Call our customer service team between 8:30 a.m. and 4:30 p.m. ET, Monday – Friday at 855.631.8328


Allergy Partners offers free educational materials to physicians and healthcare professionals to help allergy patients.