Pillow covers are sold empty, and almost nobody says so on the product page. Then the envelope arrives, and you either already own an insert that fits or you spend another twenty minutes working out what to buy. Here is the short version: for a 20 x 20 cover, buy a 22 x 22 insert.
The rest of this explains why, and what to do for every other size.
Why covers are sold without inserts
Three reasons, and only one of them is about the seller.
An insert is mostly air. Shipping one costs nearly as much as shipping something solid, because carriers bill on the size of the box rather than the weight of what is in it. Bundling an insert with a cover can double the shipping cost of an order.
Covers need washing and inserts do not. That is the entire reason covers exist as a separate product. You wash the cover, the insert stays put, and you change the look of a room for the cost of fabric rather than the cost of pillows.
And most people already have inserts. If you are replacing tired covers on pillows you already own, an insert in the box is waste.
Nothing I sell comes with an insert. I would rather say that here than have you open a box and find a flat square of fabric.
Size up by two inches
The rule is that the insert should be one to two inches larger than the cover in each direction. Two is better.
A 20 inch insert in a 20 inch cover leaves the corners empty. The fabric has nowhere to go, so it creases along the edges and the pillow sits low and slightly limp, like a cushion that has been sat on all afternoon. A 22 inch insert fills the corners, puts the cover under slight tension, and gives you the rounded, full shape that looks deliberate.
| Cover size | Insert to buy |
|---|---|
| 16 x 16 | 18 x 18 |
| 18 x 18 | 20 x 20 |
| 20 x 20 | 22 x 22 |
| 22 x 22 | 24 x 24 |
| 24 x 24 | 26 x 26 |
| 12 x 20 lumbar | 14 x 22 |
The exception is if you actively want a flat, low, sharp-cornered pillow, which reads more modern and less soft. In that case match the sizes exactly. It is a real look. It is just not the one most people are picturing when they say the pillow looks sad.
Down, feather, or polyester
Down and feather-down. The softest option and the best drape. It compresses when you lean on it and springs back when you fluff it, which is either the appeal or the annoyance depending on how you feel about fluffing. Most expensive. On a loose weave, individual quills can occasionally work their way through, so check that the cover is lined.
Feather only, without down. Cheaper and firmer, with more quills and less loft. Fine, though the gap in price between this and feather-down is usually small enough that the upgrade is worth it.
Polyester or microfiber. Holds its shape without fluffing, costs about half as much, and is the only option if feathers set off your allergies. The trade-off is that it goes lumpy after a couple of years and never drapes the way down does.
I do not sell inserts, and if I did they would not be polyester, because I do not sell synthetic fiber. But I am not going to pretend a poly insert does not work. It works, it is cheap, and for a lot of rooms it is the sensible choice.
For a handwoven cotton cover, a 22 inch feather-down insert gives the best result. The weight of the fill and the weight of the fabric suit each other.
Checking an insert you already own
Measure the insert itself, not the cover currently on it. Covers stretch, shrink and get mislabelled, so the old cover tells you very little.
Then squeeze it. If it stays compressed instead of springing back, it is finished. Putting a new cover on a dead insert is the most common reason a new pillow looks worse than the old one, and people almost always blame the cover.
One honest note
My own pillow covers are 20 x 20, patterned on both sides, lined, with an invisible zipper. They arrive empty. Buy a 22 x 22 insert alongside them and you will get the shape you are expecting on the first try.
You can see them here: Pillow Covers.
