When choosing a pillow cover for an 18×18 insert, the ideal size would typically be the same as the pillow insert, so an 18×18 cover is suitable. However, to achieve a fuller, well-stuffed look, some may prefer a slightly smaller cover, say 17×17 or 16×16, to ensure the pillow corners are well-filled and the cover fits snugly. A correctly sized cover ensures the pillow insert is not loose within the cover and maintains its shape and support.
Understanding Pillow Dimensions
Before diving into the nuances of pillow covers and inserts, it’s important to understand how pillows are measured. Pillows are typically measured across the middle, from seam to seam, and this measurement does not include the fullness of the insert. Therefore, an 18×18 pillow cover is designed to fit an insert of that size, when measured flat, corner to corner.
The Aesthetic Aspect
The decision on whether to choose the same size cover or opt for a slightly smaller one also depends on the aesthetic you’re aiming to achieve. A same-size cover will give a softer, more relaxed look, while a cover that’s slightly smaller than the insert will provide a plump appearance.
The Material Factor
Material is another factor that affects the choice of pillow cover size. Thicker, more rigid fabrics like heavy cotton or wool may not stretch as much, and therefore a cover that’s too small might be difficult to fit over an insert. In contrast, a stretchier fabric like polyester or a thinner cotton might accommodate a tighter fit without issue.
Our Top 5 Pillow Picks
Updated September 2026MFWW Cervical Contour Memory Foam Pillow
Best for neck pain. A dual-height ergonomic contour cradles your head and supports the neck, for back and side sleepers.
- Contour memory foam
- Dual-height design
- Cool breathable cover
Cooling Shredded Memory Foam Pillows, Standard, 2-Pack
Best value pair. Shredded foam you can adjust to your loft, with a cool-gel feel and no solid-block heat. Two pillows in one box.
- Adjustable shredded foam
- Cool gel
- Hypoallergenic
- Standard 2-pack
Cooling Shredded Memory Foam Pillows, Queen, Set of 4
Best for the whole household. The same adjustable cooling foam in queen size, four to a set, so every bed in the house gets an upgrade.
- Adjustable shredded foam
- Cool gel
- Hypoallergenic
- Queen set of 4
Utopia Bedding Hotel Pillows, Queen, Set of 4
Best hotel-style set. Plush, cooling pillows made to suit side, back and stomach sleepers alike. A safe pick for guest rooms.
- Queen set of 4
- Cooling
- All sleep positions
- Hotel style
Zalmureta Goose Feather & Down Pillows, Queen, Set of 2
Best luxury pick. A three-chamber goose feather and down fill wrapped in a 100% cotton shell, for that five-star-hotel feel at home.
- Goose feather & down
- 3-chamber design
- 100% cotton shell
- Queen 2-pack
Identifying the Right Pillow Cover Size
The ideal pillow cover size can depend on multiple factors, including personal preference, insert material, and where the pillow will be used. For a homey and inviting look, you might choose a cover that’s exactly 18×18 to fit your insert. For a more luxurious and rich feel, a slightly smaller cover at 16×16 or 17×17 inches can provide that overstuffed look many find appealing.
Go for a Tight Fit or Not?
Deciding if a tight fit is right for you depends on how you will use the pillow. For decorative purposes, a tighter cover can add a touch of elegance. However, for a pillow you plan to use nightly for sleep, you might prioritize comfort over appearance, choosing a cover that’s easier to remove and clean.
Sewing Your Own Pillow Covers
If you’re making your own pillow covers, knowing your insert size is crucial. When cutting fabric for an 18×18 insert, remember to account for the seam allowance. This means your fabric pieces might begin slightly larger than 18×18 before you sew them together.
Determining the Closure Type
Closure type can also greatly influence the size of the pillow cover you’ll need for your 18×18 insert. Common closure types include zippers, buttons, or envelope closures.
Zippered Closures
With zippered closures, consider that the zipper might take away some of the width of your pillow cover. Therefore, if you’re using a zippered cover that’s the exact size of the insert, the final usable area might be slightly less, making the cover feel snugger.
Envelope Closures
Envelope closures offer more flexibility in fitting the cover over the insert, but they can also look baggy if the cover is not the right size. It’s essential to ensure the overlap is generous enough to secure the insert without leaving too much excess material.
Impact of Pillow Insert Material
The fill of your 18×18 pillow insert can also determine the appropriate cover size. Down or feather inserts might require covers that are tighter to prevent the feathers from shifting and creating a lumpy appearance. On the other hand, memory foam or other firmer materials might not need as tight a cover to maintain their shape.
Down and Feather Inserts
For down and feather inserts, the snugness of the cover will ensure the pillow looks full and maintains its loft. A 17×17 or even 16×16 cover on an 18×18 down or feather insert can help to achieve this goal.
Synthetic and Foam Inserts
Synthetic fills and foam inserts retain their shape without needing a tight cover. However, to avoid a saggy or loose-looking pillow, stick to a cover that’s no more than an inch smaller than the pillow insert.
Washing and Shrinkage Considerations
Regardless of whether you’re buying or making a pillow cover, consider potential shrinkage after washing. Natural fibers like cotton can shrink, so if you’re purchasing a cover, look for pre-shrunk materials or consider buying a cover that’s slightly larger to begin with.
Maintenance and Care
When choosing your pillow cover, read the care instructions carefully. Some covers, particularly those that might shrink or are a tighter fit, might be better suited to spot cleaning or dry cleaning rather than machine washing.
Custom and Specialty Pillows
If your pillow has unique features such as decorative trim, odd shapes, or extra thickness, finding the right cover size may involve a trial-and-error process. Custom made covers could be the best option for non-standard pillows.
Adjusting to Specialty Pillows
With specialty pillows, don’t hesitate to tweak the standard sizing rules. For example, a bolster or a pillow with gussets might require a more custom fit, where measurements will vary based on the unique characteristics of the pillow.
Where to Find Pillow Covers
Pillow covers can be found in various places, from home goods stores to online marketplaces. When shopping online, pay close attention to the listed dimensions and customer reviews to ensure you’re getting a size that will suit your needs.
Custom-Made Options
If you’re struggling to find the perfect pre-made cover, or if you have specific design requirements, custom-made covers might be the solution. Many online shops and local tailors offer services to create pillow covers to your exact specifications, taking into account all the aforementioned factors.
Finishing Thoughts
Choosing the right pillow cover for an 18×18 insert comes down to a combination of personal preference, practicality, and the function of the pillow. Remember, while a same-size cover can bring a classic look, a slightly smaller cover may offer that plush, inviting style many desire. Take into account the material of both the insert and the cover, as well as closure types, cleaning requirements, and potential shrinkage. Whether you choose to buy off-the-shelf, custom-make your own, or even sew it yourself, the right cover will add both comfort and style to your living space.
