A split king adjustable bed usually uses two separate Twin XL mattresses, so the right cover needs to fit each side on its own and stay put as the bed moves. The options below include fitted waterproof protectors, a quilted pad for extra cushioning, and one split-top king product to avoid if you have a standard split king. Check your mattress dimensions and depth before ordering, since similar bed names do not always mean the same fit.
Quick Comparison
| Product | Style | Fit details | Best for |
|---|---|---|---|
| GRT Split King Waterproof Mattress Protector | Thin, three-layer waterproof cover | Two 39" × 80" pieces; mattress depth 5"–19" | Broad mattress-depth compatibility |
| Kingnex Quilted Split King Mattress Protector Pad | Quilted waterproof pad | Two 39" × 80" pieces; up to 16" deep | A softer, lightly padded surface |
| Kingnex Bamboo Viscose Split King Mattress Protector | Thin bamboo-viscose and cotton cover | Two 39" × 80" pieces; up to 18" thick | Keeping the mattress’s original feel |
| Kingnex Split Top King Mattress Protector Pad | Quilted split-top king pad | One 78" × 80" piece with a 32"–34" split at the head | Split-top king beds, not standard split kings |
| SPRINGSPIRIT Split King Waterproof Mattress Protector | Quilted waterproof protector | Two 39" × 80" pieces; listed depth details vary | A little extra surface cushioning |
Our Picks: Best Mattress Cover For Split King Adjustable Bed reviews
1. GRT: A Flexible-Fit Waterproof Protector for Separate Twin XL Mattresses
This GRT set includes two fitted covers, each sized for a 39" × 80" Twin XL mattress. Its three-layer construction pairs a microfiber top with a middle layer and TPU waterproof backing, creating a barrier against spills and other liquids without adding quilted padding.
The stretch skirt is designed for mattresses from 5" to 19" deep. That broad range may be useful if your adjustable bed has a thicker mattress or a topper, though it is still worth measuring the mattress itself before buying. The fitted design is intended to remain in place when the head or foot of the bed is raised.
The cover is machine washable and dryer friendly on low heat, with mild detergent and no bleach recommended. The product is also described as OEKO-TEX STANDARD 100 certified. Owners report that the cover can handle everyday spills while staying relatively quiet and comfortable, though the waterproof layer covers the top rather than the sides. This is a practical pick for protection, not for adding softness.
Pros:
- Two separate covers sized for standard split king mattresses
- Fitted skirt accommodates a stated depth range of 5" to 19"
- Waterproof TPU backing and machine-washable care
- Designed to stay fitted as an adjustable bed moves
Cons:
- Does not add a quilted or padded layer
- The sides are not described as waterproof
Verdict: Choose the GRT if you want a straightforward waterproof split king cover and need a wider stated mattress-depth range than several alternatives offer.
2. Kingnex Quilted Pad: Waterproof Protection with Added Loft
Kingnex’s quilted protector comes as two fitted pads, each measuring 39" × 80". A brushed polyester surface and microfiber fill add more loft than a thin, sheet-like protector, while a TPU membrane on the back is intended to block liquids from reaching the mattress.
The elastic fitted construction is designed to hold each pad in place, and the listed pocket depth goes up to 16". That limit is narrower than the GRT’s stated range, so compare it with the full depth of your mattress. The company describes the pad as quiet and breathable, and the care instructions call for a cold machine wash and low-heat tumble dry.
This style makes sense if you want some cushioning along with protection. The trade-off is that the quilted fill changes the surface more than a thin protector does. If your mattress already has the exact feel you want, a non-padded option may be a better match.
Pros:
- Two separate pieces sized for split king mattresses
- Quilted surface adds a little loft
- Waterproof backing is designed to guard against spills and perspiration
- Machine washable and described as quiet
Cons:
- Listed pocket depth is limited to 16"
- Quilting may alter the feel of the mattress more than a thin cover
Verdict: Pick the Kingnex quilted pad if a softer, lightly padded surface matters as much as waterproof protection and your mattress is no deeper than its stated limit.
3. Kingnex Bamboo-Blend Cover: A Thin Option That Preserves Mattress Feel
This Kingnex set contains two fitted protectors for 39" × 80" Twin XL mattresses. The top fabric is listed as 70% bamboo viscose and 30% cotton, with a TPU membrane on the reverse side for waterproof protection. Unlike the quilted choices, this cover has no padding.
The thin construction is intended to protect the mattress without changing its original feel. The fabric is described as soft and moisture-wicking, while the fitted design accommodates mattresses up to 18" thick and is made to stay snug as an adjustable bed changes position. It can be machine washed in cold water and tumble dried on low.
This design is a good fit if you prefer a close-to-the-mattress feel and do not need extra cushioning. The material blend may appeal to shoppers looking for a bamboo-viscose surface, but the cover’s thin profile will not soften a firm mattress in the way a quilted pad might.
Pros:
- Two pieces sized for a standard split king
- Thin, unpadded design aims to preserve mattress feel
- Waterproof backing and a stated fit for mattresses up to 18" thick
- Machine washable with low-heat drying instructions
Cons:
- Does not add cushioning or loft
- The fabric blend and feel may not suit shoppers who prefer a quilted surface
Verdict: Consider this Kingnex option if you want a thin waterproof barrier with a bamboo-viscose-and-cotton surface rather than a padded mattress layer.
4. Kingnex Split-Top King Pad: Only for a Split-Top King Configuration
This Kingnex product is a quilted waterproof pad for a split-top king bed, not a standard split king made from two separate Twin XL mattresses. It is listed as one 78" × 80" piece with a 32"–34" split at the head. That layout differs from the two independent 39" × 80" covers needed for a typical split king.
The pad has a brushed fabric surface, microfiber fill, a TPU waterproof backing, and an elastic fitted design. Its listed pocket depth is up to 16", and the care instructions call for machine washing in cold water and tumble drying on low. Those features may suit the specific split-top configuration it is made for, but they do not make it interchangeable with a standard split king protector.
Before choosing this product, check your bed’s mattress layout carefully. If you have two separate Twin XL mattresses, this is the wrong shape even if your bed is described as a king-size adjustable bed. For standard split king beds, choose one of the two-piece products in this list instead.
Pros:
- Quilted surface adds loft for compatible beds
- Waterproof backing is designed to protect against liquid spills
- Fitted style and machine-washable care
Cons:
- Not designed for two separate Twin XL mattresses
- Its one-piece split-top shape is incompatible with a standard split king
Verdict: Buy this only if you have a split-top king bed with the matching head split; skip it for a standard split king adjustable bed.
5. SPRINGSPIRIT: A Quilted Two-Piece Set with a Fit Detail to Verify
SPRINGSPIRIT’s package contains two protectors, each measuring 39" × 80", with a polyester quilted face, polyester fill, and polyurethane waterproof backing. The fitted design is made for split king beds, and the added quilting gives it more loft than a thin protector.
There is a fit detail to check before ordering: the product description says the skirt fits mattresses up to 18" deep, while a product highlight lists a depth of up to 14". Because those specifications differ, confirm the current listing details and measure your mattress rather than relying on one figure. The product is machine washable.
Owners describe the pad as soft and breathable, with little movement or noise during use. As with other quilted protectors, the added fill may change the mattress surface slightly. It is a reasonable option if you want some cushioning, but the conflicting depth information makes it less straightforward to size than the GRT protector.
Pros:
- Two separate 39" × 80" pieces for a standard split king
- Quilted surface adds some cushioning
- Waterproof backing and machine-washable care
- Owners describe it as quiet and not prone to shifting
Cons:
- Listed mattress-depth limits conflict: 14" in one detail and 18" in another
- Quilted construction may change the feel of the mattress
Verdict: Consider SPRINGSPIRIT if you want a quilted two-piece set, but verify the pocket-depth limit with the listing before buying.
How to Choose a Mattress Cover for a Split King Adjustable Bed
Confirm That Your Bed Is a Standard Split King
A standard split king typically uses two separate Twin XL mattresses, each measuring 39" × 80". Look for a protector sold as two individual pieces in those dimensions. A split-top king is different: it uses a single king-size cover with a split near the head. The Kingnex split-top product in this guide is made for that alternate layout, not two separate Twin XL mattresses.
Measure Mattress Depth, Including Any Topper
Measure from the bottom edge to the top sleeping surface, including a mattress topper if you use one. Compare that measurement with the product’s pocket-depth range. A cover that is too shallow may not stay securely fitted, while a very loose fit can bunch during movement. Pay special attention to SPRINGSPIRIT’s conflicting depth details and confirm the current specification before ordering.
Choose Between a Thin Cover and a Quilted Pad
A thin protector, like the Kingnex bamboo-blend option, adds a waterproof barrier without much extra loft. That can suit you if you want to preserve the feel of your mattress. A quilted pad, like the Kingnex or SPRINGSPIRIT options, adds some cushioning, but it may change the surface feel. Think about whether you want protection alone or a little padding as well.
Check the Waterproof Layer and Coverage
The products here describe waterproof backing, including TPU or polyurethane layers, to help block liquids from reaching the mattress. Check which parts of the cover are protected: the GRT description, for example, specifies a waterproof top but does not describe waterproof sides. If liquid protection is your main concern, read the construction details closely rather than assuming every surface is sealed.
Look for a Secure Fitted Design
An adjustable base changes the bed’s position, so a fitted skirt and suitable pocket depth matter. The covers in this guide use fitted designs intended to stay in place, but a good fit still depends on matching the protector to your mattress size and depth. After putting it on, adjust the bed through its usual positions and check that the corners remain secure.
Review the Care Instructions
Waterproof protectors need washing from time to time, so check the care requirements before you buy. The options here generally allow machine washing, but drying instructions vary. Follow the specific product directions, including the recommended water temperature and low-heat limits, to help avoid damage to the waterproof backing.
Frequently Asked Questions
What size mattress cover fits a standard split king adjustable bed?
A standard split king usually has two Twin XL mattresses, each measuring 39" × 80". Choose a set with two covers in that size, and confirm the pocket depth matches your mattresses.
Can I use a regular king mattress protector on a split king bed?
A regular king protector is made for one 76" × 80" mattress, while a standard split king has two separate mattresses. A single regular king cover may not fit or move properly with the separate adjustable sections. Choose a product specifically sized for a split king.
Is a split-top king the same as a split king?
No. A standard split king uses two separate Twin XL mattresses. A split-top king uses one king-size mattress or cover with a split near the head. Check the bed’s mattress layout before ordering; the Kingnex split-top pad listed here is not for a standard split king.
Will a mattress protector stay in place when the bed moves?
These products use fitted designs intended for adjustable beds, but fit depends on choosing the correct size and pocket depth. Measure your mattress and check that the corners remain secure as you raise and lower the bed.
Do quilted mattress protectors change how a mattress feels?
They can. Quilted pads have added fill and loft, so they may make the surface feel softer or more padded. A thin, unpadded protector is a better choice if you want to keep the mattress feel as close to its original state as possible.
Are these split king mattress covers waterproof on the sides?
Do not assume that they are. Product construction details may specify a waterproof layer on the top or backing without stating that the sides are protected. Check the individual product description if side coverage is important to you.
Which option is best if my mattress is unusually thick?
Compare your mattress depth with each product’s stated pocket range. The GRT cover lists a range from 5" to 19", while the Kingnex bamboo-blend cover is listed for mattresses up to 18" thick. SPRINGSPIRIT’s details conflict, so verify its current specifications before choosing it.
Final Recommendation
For most standard split king adjustable beds, the GRT protector is the most flexible choice in this group: it comes as two Twin XL covers, has a broad stated mattress-depth range, and offers waterproof protection without quilted padding. If you want more surface loft, consider the Kingnex quilted pad, provided your mattress fits its depth limit. The Kingnex bamboo-blend option is a strong alternative if you prefer a thinner cover, while the split-top Kingnex pad should be reserved for a matching split-top king bed.
