A mattress gap between your bed and a headboard or wall can catch pillows, phones, and other small items. A mattress extender or gap filler is designed to occupy that space, and some styles also provide a soft surface to lean against. The right choice depends on the gap’s length and depth, how closely the filler fits, and whether you want a standard size or a custom one.
Below, we compare five foam-filled options. Check the dimensions and selected size on the product page before ordering: a filler that is too short or too narrow may leave gaps, while one that is too large may not sit securely.
Quick Comparison
| Product | Standout feature | Best suited for |
|---|---|---|
| DEEPSHARK Bed Gap Filler | 45D foam and a removable linen cover | Shoppers who want a choice of sizes and colors |
| ThinMay Bed Gap Filler, Dark Gray | Multiple listed widths for different bed sizes | Those looking for a standard width option |
| FAJOME Custom Bed Gap Filler | Made to the dimensions you provide | Unusual or hard-to-match gaps |
| ThinMay Bed Gap Filler | Foam insert and washable cover | Buyers comparing a standard-size option |
| WUIOYNF Mattress Extender | Eight listed mattress-width options | Those who need a less common width |
Our Picks: Best Mattress Extenders And Gap Fillers reviews
DEEPSHARK Bed Gap Filler: Foam Support with a Removable Cover
DEEPSHARK’s filler is meant to sit between a mattress and a headboard or wall, filling the space rather than acting as a simple cover over it. The brand lists 16 size options and describes the insert as high-density 45D sponge. Since the exact measurements matter more than the bed-size label, check the selected option against your gap before buying.
The cover is made from linen fabric and has a zipper for removal. The product information says it can be machine- or hand-washed, with low-heat tumble drying or air drying recommended. The foam is compression-packed and may need 48 to 72 hours to fully expand after unpacking, so plan to let it rest before judging its final shape.
This option also comes in light and dark color choices and can be used as a wedge-style headboard pillow or sofa back support. Its stated foam density and size selection make it a flexible pick, though the listing does not provide all the individual measurements in the supplied description. Confirm the exact size and color available for your setup.
Pros:
- Listed in 16 size options.
- 45D foam insert is designed for support and resilience.
- Removable, washable cover.
- Can also be used against a wall or as sofa back support.
Cons:
- Needs time to expand after unpacking.
- You’ll need to confirm the exact measurements for your chosen size.
Verdict: Choose DEEPSHARK if you want a washable, foam-filled option with many size choices and are willing to check the dimensions carefully.
ThinMay Dark Gray Gap Filler: Several Standard Widths
This ThinMay model is designed to fit along the gap between a mattress and a headboard or wall. Its description lists widths of 39, 54, 60, 72, and 76 inches, covering several common bed sizes. It also gives a nominal product size of 76 by 2 by 8 inches, so compare that information with the dimensions shown for the specific option you select.
The insert uses foam described as high-density and resilient, while the cover is breathable linen fabric with a removable, washable design. The filler can also serve as a long cushion against a wall or as support on a wooden sofa. These extra uses may be handy, but its main job is to fill a mattress gap; it does not replace a wider mattress.
Compared with the custom FAJOME option, this model relies on preset widths rather than measurements you provide. That makes it simpler if one of the listed sizes matches your bed, but less suitable if your gap has unusual dimensions. The listing notes a small size tolerance, so exact fit should not be assumed.
Pros:
- Several preset widths are listed for different bed sizes.
- Removable cover can be washed.
- Foam insert is intended to fill the gap and provide support.
- Can be used as a cushion against a wall or sofa.
Cons:
- Preset widths may not match an unusually sized gap.
- Check the selected option’s dimensions, as the listing includes more than one measurement detail.
Verdict: This ThinMay option makes sense when a listed width matches your bed and you prefer a standard-size filler over a custom order.
FAJOME Custom Gap Filler: A Made-to-Measure Choice
FAJOME’s main distinction is its made-to-measure approach. The product description says you can provide your desired dimensions for gaps between a mattress and headboard, a mattress and wall, or two mattresses. That can be useful when a standard bed-size option leaves a space uncovered or extends too far.
The insert is described as 50D foam, with a linen cover and a zipper for removal and washing. The snug-fit design is intended to fill the opening and help keep small items from falling between the mattress and the surface behind it. It can also be used as a headboard wedge pillow or mattress extender.
Custom sizing can be more precise, but it puts more responsibility on you to measure accurately and enter the dimensions correctly. Check the product page for its available measurement choices and ordering instructions before placing an order. Unlike the other picks here, the supplied description does not give a set list of standard widths to choose from.
Pros:
- Made to the dimensions you provide.
- Useful for gaps between a mattress and wall, headboard, or another mattress.
- 50D foam insert and removable linen cover.
- Can double as a wedge pillow.
Cons:
- Accurate measuring and order details are especially important.
- The supplied description does not list preset widths or a standard size range.
Verdict: FAJOME is the strongest match for a nonstandard gap, provided you can measure the space carefully and confirm the custom-order details.
ThinMay Bed Gap Filler: A Simple Foam-and-Linen Design
This ThinMay product uses the same core design and listed size range as the other ThinMay option in this comparison: a foam insert with a breathable linen cover, intended to fit into the space behind a mattress. The listed widths are 39, 54, 60, 72, and 76 inches. The description also gives a nominal dimension of 76 by 2 by 8 inches, so check the product page to make sure you choose the size that fits your arrangement.
The removable cover is described as washable, and the foam is intended to provide support when filling a gap or leaning against a headboard. It may also be used as an elongated cushion or as support on a wooden sofa. For a typical bed setup, the key decision is whether one of its preset widths covers the length of your gap.
This model is similar in function and listed specifications to the dark gray ThinMay pick above, so it is not a distinct upgrade based on the supplied product information. Compare the listing’s size, color, and current availability before choosing between them. As with any foam filler, fit depends on the actual measurements of both your mattress and the gap.
Pros:
- Several widths are listed for common bed sizes.
- Removable cover is washable.
- Can be used as a headboard support or elongated cushion.
Cons:
- Preset sizing may not suit a custom gap.
- The supplied details closely overlap with the other ThinMay option, so compare the individual listing carefully.
Verdict: Consider this ThinMay model if its listing offers the size and color you want, but compare it closely with the similar ThinMay option before deciding.
WUIOYNF Mattress Extender: Eight Listed Width Options
WUIOYNF lists eight widths: 39, 47, 54, 60, 70, 72, 76, and 78 inches. That range includes some less common measurements alongside standard bed widths, giving you more preset choices than the ThinMay options in this guide. Check the exact selected size on the product page, particularly if your mattress is an unusual width.
The filler has a linen cover and an insert described as high-density, resilient foam. Its intended uses include filling the seam between a mattress and a headboard or wall, leaning against a headboard, and supporting your back on a sofa. The design is meant to fit into the gap rather than simply lie over it.
This is a practical alternative to custom sizing if one of its eight widths matches your needs. However, the supplied description does not specify a foam density number or give care instructions for the cover. If those details matter to you, check the listing before ordering.
Pros:
- Eight listed widths, including 47, 70, and 78 inches.
- Designed to fill a mattress gap rather than just cover it.
- Can also be used as a headboard or sofa support cushion.
- Linen cover and resilient foam are specified.
Cons:
- The supplied description does not state a foam density number.
- Cover care details are not provided in the supplied product information.
Verdict: WUIOYNF is worth considering if its broader set of preset widths includes the exact size you need and you do not require a specified foam-density rating.
How to Choose a Mattress Extender or Gap Filler
Measure the Gap Before Choosing a Size
Measure the length of the space you want to fill and the distance between the mattress and the headboard or wall. Also consider the filler’s height and depth so it sits at a useful level beside your mattress. For a custom product, take measurements carefully and follow the seller’s instructions. For a preset size, compare the listed dimensions with your measurements rather than relying only on a bed-size label.
Choose Between Preset and Custom Sizing
Preset-width models are straightforward when one of the listed options matches your bed. WUIOYNF offers the broadest stated set in this group, while the ThinMay models list a smaller selection. FAJOME is designed for custom measurements, which may help with an unusual layout but requires accurate measuring and careful entry of the requested dimensions.
Consider the Foam and Its Intended Use
Foam details vary across the products. DEEPSHARK specifies 45D sponge, and FAJOME describes its insert as 50D foam. ThinMay and WUIOYNF describe their foam as high-density or resilient without providing the same numeric density detail. If you plan to lean against the filler, look for a design and size that provide enough support for that use.
Check the Cover and Care Instructions
A removable, washable cover can make routine cleaning easier. DEEPSHARK, both ThinMay options, and FAJOME describe removable covers. WUIOYNF’s supplied description does not specify care instructions, so check its listing if washability is a priority. Follow the product’s own care guidance to avoid damaging the fabric or insert.
Allow for Expansion and Fit
Some foam products are compression-packed. DEEPSHARK states that its filler may take 48 to 72 hours to fully expand after unpacking. Give compressed foam the time specified by the seller before assessing its shape. Also check how the filler sits between the mattress and the surface behind it; a gap filler is not a replacement for a larger mattress and may not solve a gap that is too wide for its dimensions.
Think About Color and Other Uses
If the filler will remain visible, consider how its cover color fits your room. DEEPSHARK lists light and dark color choices, while other product colors may depend on the listing. Several of these cushions can also be used against a wall or as sofa support, but choose based on the dimensions and support you need for the primary bed-gap use.
Frequently Asked Questions
What does a mattress gap filler do?
It sits in the space between a mattress and a headboard or wall. Its purpose is to fill the opening, reduce the chance of small items falling into it, and, in some designs, provide a soft surface to lean against.
Can a gap filler make my bed wider?
It can occupy a gap and create a more continuous surface near the headboard, but it does not make the mattress itself wider. Measure your setup and choose a filler with dimensions suited to the space.
How do I measure for a bed gap filler?
Measure the length of the gap and the space between the mattress and the wall or headboard. Check the filler’s length, height, and depth against those measurements, and follow the seller’s sizing instructions if ordering a custom option.
Are mattress gap fillers washable?
Several products in this guide describe removable, washable covers. Care details differ, so check the individual product instructions. DEEPSHARK lists machine or hand washing and recommends low-heat tumble drying or air drying.
How long does compressed foam take to expand?
Expansion time depends on the product. DEEPSHARK states that its foam may take 48 to 72 hours to fully expand after unpacking. Follow the instructions for the specific filler you choose.
Can I use a bed gap filler between two mattresses?
Some models are described as suitable for the space between two mattresses. FAJOME specifically lists that use. Check the product dimensions and instructions to make sure the filler fits the seam in your arrangement.
Final Recommendation
For a nonstandard space, FAJOME stands out for its made-to-measure design, while WUIOYNF offers the widest stated range of preset widths. DEEPSHARK is a useful choice if you want a removable cover and a stated 45D foam insert. Before choosing any option, compare its exact dimensions with your mattress and gap; a close fit matters more than the product’s bed-size label.