A mattress topper goes under a mattress protector. The protector’s job is to shield your mattress (and topper) from spills, dust mites, and stains. Placing the protector over the topper keeps both clean and prevents the topper from shifting. Never put a protector under a topper, that defeats its purpose.
A mattress protector is a thin, often waterproof or allergen-blocking layer designed to encase the top and sides of your mattress. A mattress topper is a thick, comfort-altering layer (memory foam, latex, down, or polyfoam) that sits on top of the mattress to change its feel. If you put the topper on top of the protector, the protector can’t safeguard the topper from sweat, spills, or dust mites. If you put the protector under the topper, the topper itself becomes a sponge for stains and allergens, and you’ll have to wash a bulky topper far more often than necessary.
This sandwich method keeps the topper clean, reduces wear, and makes maintenance easy, just wash the protector and sheets, not the topper.
Standard mattress protectors are designed for mattresses 8-12 inches thick. Adding a 2-4 inch topper means you need a protector with deep pockets (14-18 inches). If your current protector is too small, buy a new one. Look for “deep pocket” or “extra deep” labels. If you’re shopping for a topper, check our best memory foam mattress topper guide for options that pair well with protectors. For a broader look at materials and thicknesses, visit the mattress topper buying guide.
A topper can extend the life of a mattress that’s only slightly too firm or too soft. But if your mattress is over 8 years old, sagging, or causing back pain, a topper is a temporary fix. A protector won’t fix structural issues like broken coils or compressed foam. In that case, replacing the mattress is the smarter investment. You can still use a topper on a new mattress to fine-tune its feel, just follow the same layering order. Browse our category of mattress toppers for options that work on both old and new beds.
| Layer | Purpose | Position |
|---|---|---|
| Mattress | Base support | Bottom |
| Mattress topper | Adds softness or pressure relief | On mattress |
| Mattress protector | Blocks spills, dust mites, stains | Over topper |
| Fitted sheet | Comfort and hygiene | Over protector |
Yes, but that leaves the topper unprotected. The topper will absorb sweat and spills, and you’ll need to wash it often, which shortens its lifespan. Unless you’re using a cheap topper you plan to replace soon, always put the protector over the topper.
Most protectors are thin and breathable, so they won’t change the feel of your topper. Avoid vinyl or “plastic” protectors, they can trap heat and make the topper feel firmer. Look for a stretch-knit or cotton protector with a waterproof membrane for minimal change in comfort.
Measure the total height of your mattress plus topper, then buy a protector with deep pockets that match that height. Many brands sell protectors up to 18 inches deep. If your topper is 4 inches and your mattress is 12 inches, you need at least a 16-inch pocket.