How to Choose the Right Pillow Insert for Your Decorative Pillow Covers

Quick answer

To choose the right pillow insert, match the insert size to your cover size—go up 1-2 inches for a plump look—and pick a fill based on the feel you want: down for softness and polyester for structure and easy care. For square covers, buy a square insert that is 1-2 inches larger; for lumbar covers, choose a lumbar insert with the same width but slightly taller height to fill the shape.

Decorative pillow covers come in all shapes and sizes, but the insert you put inside determines how they look and feel. A limp or overstuffed pillow can ruin the aesthetic of your sofa or bed. Whether you're refreshing your living room or adding a pop of color to your bedroom, understanding pillow insert size and fill is key.

This guide breaks down the factors that matter: size, fill material, and firmness. We'll give you clear decision rules and trade-offs so you can confidently choose the right insert for your covers—no guesswork needed.

Why Pillow Insert Size Matters

The most common mistake is buying an insert that's exactly the same size as the cover. When you do that, the pillow looks deflated and the cover doesn't hold its shape. The general rule is to size up: for a 18"x18" cover, choose a 20"x20" insert. This extra 2 inches fills out the corners and gives a plump, inviting look.

If you prefer a softer, more relaxed look, you can go with just 1 inch larger. But for a structured, high-end appearance, 2 inches is the sweet spot. Keep in mind that down inserts compress more than polyester, so you may need a larger size to achieve the same fullness.

• For a 18" square cover, use a 20" square insert for a plump look.
• For a 12"x20" lumbar cover, consider a 12"x22" lumbar insert to fill the length.
• Always measure your cover before buying—sizes can vary by brand.

Down vs. Polyester: Choosing the Right Fill

The fill material determines the pillow's feel, support, and care requirements. Down inserts are made from duck or goose feathers and offer a soft, luxurious feel that molds to your body. They're great for lounging but require fluffing and may cause allergies in some people. They also tend to be more expensive and need professional cleaning.

Polyester inserts are more affordable, hypoallergenic, and easier to care for—most are machine washable. They provide a firmer, more structured shape that holds up well over time. However, they can feel less plush and may flatten with heavy use.

Consider your priorities: if you want a sink-in softness and don't mind extra maintenance, down is a good choice. If you need something durable, budget-friendly, and low-maintenance, polyester is a practical alternative.

• Down inserts: soft, luxurious, but require fluffing and can be pricey.
• Polyester inserts: firm, affordable, and easy to clean—great for high-traffic areas.

Square vs. Lumbar: What's the Difference?

Square inserts are the most common and come in sizes like 16", 18", 20", and 22". They work well on sofas, beds, and chairs. Lumbar inserts are rectangular and typically measure 12"x20" or 12"x22". They provide lower back support and are ideal for adding variety to a seating arrangement.

When choosing an insert, match the shape to your cover. For square covers, a square insert is essential; using a lumbar insert in a square cover won't fill it properly. Similarly, for lumbar covers, a square insert will leave gaps at the ends. Always buy the same shape as your cover for the best fit.

• Square inserts: versatile, available in multiple sizes.
• Lumbar inserts: perfect for back support and visual interest.

Decision Rules for Choosing a Pillow Insert

• Size rule: Always measure your cover and add 1-2 inches to the insert size. For square covers, go 2 inches up for a plump look. For lumbar covers, add 2 inches to the length. Check your cover's dimensions before ordering.
• Fill rule: Choose down for softness and luxury, but be ready for maintenance. Choose polyester for structure, hypoallergenic properties, and easy cleaning. Down for comfort, polyester for convenience.
• Shape rule: Match the insert shape to your cover: square inserts for square covers, lumbar inserts for lumbar covers. Don't mix shapes. Same shape ensures a full, even appearance.

Product Spotlight: Pillow Inserts from Hawkins New York

• Essential Dinnerware, 16 Piece Set - Bone: While not a pillow insert, this stoneware set shows the brand's commitment to quality and design, with a complete 16-piece set for four, featuring soft rippling and a hand-thrown feel. When styling your home, matching the aesthetic of your dinnerware to your pillow inserts can create a cohesive look. This set's neutral Bone color pairs well with a variety of pillow covers.
• Hand Blown Highball - White/Grey: Hand blown highball glass by Bow Glassworks, based in upstate NY. The ultimate gift for your cocktail loving friends (or yourself). We love them for spritzes and showcased on open shelving. Just as a highball glass adds a handcrafted touch to your bar, a quality pillow insert adds a finished look to your seating. Both elevate everyday moments.

Which Insert Should You Choose?

Best for

• Down inserts: best for low-traffic areas like bedrooms where you want a soft, luxurious feel and don't mind fluffing.
• Polyester inserts: best for high-traffic areas like living rooms, where durability and easy care are priorities.

Not for

• Down inserts: not for allergy sufferers or those seeking low-maintenance options.
• Polyester inserts: not for those who prefer a very soft, moldable pillow that mimics down.

Choosing the right pillow insert comes down to size, fill, and shape. By following the decision rules above, you can ensure your decorative pillows look plump and inviting. Remember to measure your covers, decide on the feel you want, and match the shape. With these tips, you'll create a comfortable and stylish space.