How to Choose Pillow Covers and Inserts for Comfort

Quick Answer

Buy the insert one size larger than the cover for a full, comfortable look, and measure the cover's finished dimensions rather than the old insert. For most sofas, a 22-inch insert in a 20-inch cover is the sweet spot; for a firm backrest, go up two sizes. If you want a soft, slouchy pillow, match the insert to the cover size instead.

Pillow comfort comes down to two things most people get backwards: the insert size relative to the cover, and the fill. Get those right and a sofa looks intentional; get them wrong and even good covers look limp or overstuffed.

This guide answers the questions we hear most often, from measuring a cover to choosing between down, down-alternative, and polyester, plus how to keep pillows from flattening over time.

How do I measure a pillow cover correctly?

Measure the cover flat, seam to seam, across the middle, not the corners. If the cover is piped or has a flange, measure only the sewn body, since the trim doesn't count toward the insert size. For a square cover, check both width and height; small variations are normal in handmade textiles.

If you're replacing an insert, don't trust the old one's label. Inserts compress and lose loft, so a cover that once fit a 20-inch insert may now need a 22-inch one to look full. Measure the cover itself, then size up.

• Measure seam to seam, not corner to corner.
• Ignore piping, flange, and fringe when sizing.
• When in doubt, size up one inch rather than down.

What size insert should I use for my pillow cover?

The general rule is one size up: a 20-inch cover takes a 22-inch insert, an 18-inch cover takes a 20-inch insert. This extra inch fills the corners and gives the pillow a tailored, comfortable shape that holds up when you lean on it.

For a firmer backrest or a pillow that gets heavy use, go up two sizes. For a soft, relaxed look, match the insert to the cover size. Lumbar covers follow the same logic: a 14x22 cover takes a 16x24 insert for a full look.

• Square: cover size + 2 inches = insert size.
• Lumbar: add 2 inches to both dimensions.
• Firm backrest: add 4 inches total instead of 2.

Which fill is best for comfort?

Down and feather inserts are the softest and most forgiving; they compress under your back and bounce back when you stand up. They need occasional fluffing and aren't the best choice for allergy-sensitive homes.

Down-alternative and polyester inserts hold a firmer shape, cost less, and are easy to clean, but they can feel springy and may flatten faster with daily use. For decorative pillows that mostly sit still, a polyester insert is perfectly fine; for pillows you actually lean on, down or a down blend is worth it.

• Down: softest, best for lounging, needs fluffing.
• Down-alternative: firm, affordable, easy to clean.
• Polyester: good for decorative-only pillows.

How do I keep pillows from looking flat?

Fluff daily by grabbing opposite corners and pulling, then karate-chop the top edge to restore height. Rotate pillows weekly so the same side isn't always compressed against the sofa. If an insert has lost its loft permanently, replace the insert rather than the cover; covers usually outlast fills.

A too-small insert is the most common cause of a flat-looking pillow. Before buying new covers, check whether the current insert is actually the right size for the cover.

• Fluff daily; rotate weekly.
• Replace inserts before covers.
• A flat pillow is often a sizing problem, not a fill problem.

Can I use the same insert for different covers?

Yes, if the covers share the same finished dimensions. Keep one insert per cover size and swap covers seasonally. If you mix sizes, label the inserts with a fabric marker so you're not guessing later.

For a coordinated sofa, a common setup is two 22-inch inserts for large square covers and two 14x22 inserts for lumbar covers. That gives you enough variety to layer without buying a new insert for every cover.

• One insert per cover size is enough.
• Label inserts if you store them.
• Two squares plus two lumbars covers most sofas.

Pillow Sizing and Comfort Checklist

Measure the cover, not the old insert

Lay the cover flat and measure seam to seam across the middle, ignoring piping and flanges. Write the number down before you shop.

Size up one inch for a full look

A 20-inch cover takes a 22-inch insert; go up two sizes for a firm backrest. If the cover looks loose, the insert is too small.

Match fill to use

Down for lounging, down-alternative for firmness and easy care, polyester for decorative-only pillows. Replace the insert before you replace the cover.

Product Facts That Matter for Pillow Styling

• Fairmount Leather Round Mirror: Hand-stitched leather frame with a living finish; available in Tan or Black Harness, and in Long Oval, Wide Oval, and Round styles. The mirror's leather tones and shapes give you a reference for coordinating pillow covers, so the textiles and the wall piece feel intentional rather than accidental.
• Pair of Ceramic Table Lamps - Black: Hand-built with a matte black glaze and black tapered Belgian linen shades; sold as a pair and final sale. Matte black and linen are neutral anchors, so pillow covers in similar tones will read as calm and cohesive instead of competing.

Choosing pillow covers and inserts is mostly about measuring honestly and sizing up. Get the insert right and the cover does the rest.