If you’re searching for the best mattress extender queen to king, first check what kind of “extender” you need. A queen mattress is narrower than a king, and none of the products below adds the full width needed to turn one into the other. These are gap fillers: they help close spaces between a mattress and a wall or headboard, or between two mattresses. If your goal is a wider sleeping surface, you’ll need a suitable mattress setup rather than a gap filler.
The options below vary in length, shape, and materials. Check the gap you want to fill and the product’s measurements before choosing, especially if you need a piece to span the head of the bed.
Quick Comparison
| Product | Standout feature | Best suited for |
|---|---|---|
| M Mute Touch 78-Inch Foam Gap Filler | Uncovered foam strip that can be cut to length | Customizing a longer filler for different gaps |
| ThinMay Covered Bed Gap Filler | Removable, washable linen-style cover | Shoppers who want a covered filler in a specific length |
| ThinMay 76-Inch Bed Gap Filler | Covered foam design listed at 76 inches long | Filling a gap across a mattress with a washable cover |
| YUURO 79-Inch T-Shape Mattress Extender | T-shaped foam for gaps listed at 0.8 to 2 inches | Closing a narrow headboard or wall gap |
Our Picks: Best Mattress Extender Queen To King reviews
Best Cut-to-Fit Option: M Mute Touch 78-Inch Foam Gap Filler
The M Mute Touch is a long strip of high-density foam made to fill a space beside a mattress, such as the gap between a bed and a wall or headboard. At 78 inches long, it can span much of a bed’s width, and the description says you can cut it with scissors to adjust its length.
Its plain, uncovered foam design keeps the product simple, but it also means there is no removable fabric cover for washing. The listed fit range is for gaps from 4 to 8 inches, so this is a better match for a broad opening than for a narrow crack. The textured surface is intended to help it grip beneath the mattress. It arrives compressed and needs time to expand before use.
This is the most adaptable choice in the group if you need to trim a long filler to suit your bed. It is not a queen-to-king mattress converter: it fills a gap, and the foam strip itself does not create a full king-size sleeping surface.
Pros:
- Long foam strip can be cut to a shorter length.
- Designed for gaps from 4 to 8 inches.
- Can also be used for other gaps, such as sofa crevices.
Cons:
- Uncovered foam may be less convenient to keep clean than a removable-cover design.
- Needs time to expand after unpacking.
Verdict: Choose this one if you want a long, customizable foam strip for a wider gap and do not need a washable cover.
Best Covered Design: ThinMay Removable-Cover Bed Gap Filler
This ThinMay filler pairs a foam core with a linen-style cover. The cover is described as removable and washable, which may make routine care easier than it is with an uncovered foam strip. The product description lists several lengths, from 39 to 76 inches, for different bed setups.
It is designed to close a gap at the head of a bed or beside a mattress, and the foam can also serve as a long support cushion against a wall or sofa. Choose the length that matches the span you need to fill, rather than assuming that a “queen” or “king” label means it will widen a mattress. The listed sizes describe the filler, not a complete queen-to-king conversion.
The supplied product information marks this listing as unavailable, so check the product page before planning around it. If it is available, its washable cover is the main reason to consider it over the bare-foam M Mute Touch option.
Pros:
- Removable cover is described as washable and dryer-safe.
- Multiple listed lengths provide options for different bed spans.
- Can also be used as a long cushion or support against a wall or sofa.
Cons:
- Supplied listing information marks it unavailable; check current availability.
- You need to select the right listed length for your gap.
Verdict: This is worth considering if a washable cover matters most, provided the listing is available and its measurements suit your bed.
Best 76-Inch Covered Filler: ThinMay Bed Gap Filler
This ThinMay version is listed at 76 by 2 by 8 inches and uses a foam filling with a removable, washable cover. Its 76-inch length may suit shoppers who want a long filler across a bed, while the cover offers a practical advantage over the uncovered M Mute Touch strip.
The description gives the same general uses as the other ThinMay model: filling a gap near a headboard or wall, adding support along a sofa, or serving as a long cushion. Measure your opening before ordering. The listed length alone does not tell you whether the filler will fit the gap’s width or depth, and it does not add the full width needed to turn a queen mattress into a king.
The supplied product information marks this listing as unavailable. Its features may suit shoppers looking for a covered 76-inch filler, but availability and exact fit should be confirmed on the product page before you choose it.
Pros:
- Listed dimensions are 76 by 2 by 8 inches.
- Removable cover is described as washable and dryer-safe.
- Can be used at a bed gap or as a long support cushion.
Cons:
- Supplied listing information marks it unavailable; check current availability.
- The listed 2-inch dimension may not suit every gap shape or opening.
Verdict: Consider this model if its 76-inch length and covered design match your setup, but verify availability and dimensions first.
Best for Narrow Gaps: YUURO 79-Inch T-Shape Mattress Extender
The YUURO is a 79-inch foam filler with a T-shaped design. It is intended to sit between the mattress and a headboard or wall, helping close a narrow gap and keep pillows or small items from slipping into the space. The listed gap range is 0.8 to 2 inches.
Unlike the M Mute Touch strip, this model is designed for a much narrower opening, so it is not the right choice for a gap several inches wide. Its length can be cut to fit a shorter span, according to the product description. The T shape and firmer foam are intended to help it stay in place, but fit depends on the shape of your mattress, bed frame, and gap.
Of the four options, this is the clearest match for someone with a thin headboard gap rather than a broad opening. It remains a gap filler, not an attachment that increases a queen mattress to king width.
Pros:
- Long 79-inch design can be cut to a shorter length.
- Designed for narrow gaps from 0.8 to 2 inches.
- T shape is intended to help close the space between a mattress and a wall or headboard.
Cons:
- Not designed for gaps wider than 2 inches.
- Does not provide a washable cover, according to the supplied description.
Verdict: Pick the YUURO if your main problem is a narrow gap at the head of the bed and its T-shaped profile fits your setup.
How to Choose a Mattress Gap Filler
Be clear about what you want to extend
A gap filler closes an opening beside or between mattresses; it does not turn a queen mattress into a king. If your goal is a wider sleep surface, make sure you are shopping for a mattress or bed arrangement designed to provide that extra width. Choose a gap filler only when you want to block a space near a wall, headboard, or adjoining mattress.
Measure the gap’s width and length
Measure both the length of the space you want to cover and how wide or deep the gap is. A long strip may span the head of a bed but still be too narrow or too thick for the opening. The M Mute Touch is described for wider gaps, while the YUURO is meant for a much narrower range. Compare the product’s stated measurements with your own before ordering.
Choose between covered and uncovered foam
An uncovered foam strip is simple and can be trimmed, but it does not have a removable fabric cover. The ThinMay models are described with washable covers, which may be more convenient for care. Check the listing’s care instructions and dimensions, and do not assume that every cover or filling can be cleaned the same way.
Consider length and trimming
Some of these fillers are longer than a particular bed needs. The M Mute Touch and YUURO descriptions say their foam can be cut, but trimming may affect the finish and shape. Measure first, and only cut a product if its instructions support doing so. For a covered filler, check whether the cover can be adjusted along with the foam.
Match the filler to the bed setup
A filler intended for a headboard gap may not work as a connector between two mattresses. Look at the product’s shape and intended placement, then consider how your mattress, frame, and wall meet. A T-shaped design may suit a narrow headboard gap, while a long rectangular strip may be more appropriate for a broader opening.
Check availability and listing details
Product availability can change, and the supplied information marks both ThinMay listings as unavailable. Confirm that a product can be ordered and that its current listing still matches the dimensions and features you need. If an exact measurement is important, check the product page before making your decision.
Frequently Asked Questions
Can a mattress extender turn a queen bed into a king?
No. The products here are gap fillers, not devices that add the full width needed to convert a queen mattress into a king-size sleep surface. They are meant to close spaces near a mattress, wall, headboard, or adjoining bed.
What is a mattress gap filler used for?
It fills a space where a mattress meets a wall or headboard, or where two mattresses meet. This can help keep pillows and small items from slipping into the gap.
Which option is meant for the widest gap?
The M Mute Touch description lists a fit range of 4 to 8 inches. Measure your opening and check the product details to make sure it suits the gap’s shape and depth.
Which option is best for a narrow headboard gap?
The YUURO is listed for gaps from 0.8 to 2 inches and has a T-shaped design. It may be a better match for a narrow opening than the wider-gap M Mute Touch strip.
Are the ThinMay fillers washable?
The ThinMay descriptions say the cover is removable and washable and supports washing and drying. Follow the care guidance on the current product listing.
Do foam gap fillers need time to expand?
The M Mute Touch is described as vacuum-packed and may need up to 48 hours to fully expand after opening. Check the instructions for the specific product you buy, since packaging and setup can differ.
Can I cut a mattress gap filler to fit?
The M Mute Touch and YUURO descriptions say their foam can be cut to length. Confirm the instructions for your chosen product before trimming, especially if it has a cover or a shaped profile.
Final Recommendation
For a wide, adjustable gap, the M Mute Touch is the most flexible pick thanks to its long cut-to-fit foam strip. For a narrow opening at the headboard, the YUURO’s stated gap range makes it the more targeted option. If a washable cover is your priority, compare the ThinMay models, but confirm availability and fit before ordering. None of these products converts a queen mattress into a king, so choose based on the gap you need to fill—not on the mattress size you hope to create.