Throw Pillow Sizes and Insert Sizes

This tool helps you find throw pillow sizes for a cover you already have. Enter the size of the cover, and it shows the insert size that five pillow guides recommend, the range across those guides, and the pillow sizes that suit the back and front of a sofa.

The guides do not always agree, so the tool lists each one separately instead of picking a single answer. Results are calculated from your inputs and typical sizes from the named sources. The page covers decorative throw pillows and covers, not bed pillows.

The tool runs in your browser, nothing you enter is uploaded, and there is no sign-up. It is free to use.

How to use the throw pillow size tool

1. Choose your units under “Units”: inches or centimeters.
2. Enter the “Cover width” of your pillow cover.
3. Enter the “Cover height (leave empty for a square)”. Leave it empty if the cover is square.
4. Choose a “Sofa seat depth”: “Skip the sofa sizes”, “Shallow sofa”, “Standard sofa” or “Deep sofa”. Pick “Skip the sofa sizes” if you only need insert sizes.
5. Read “Insert size, by guide”. Each guide is lettered in the tool (T, Z, C, P and H), so you can compare them side by side.
6. Check “Range across the guides” for the smallest and largest suggested insert.
7. If you chose a sofa depth, read “Pillow sizes for this sofa” for the back and front pillows.

The tool starts with a 20 in square cover and a standard sofa. The preset buttons “20 in cover”, “18 in cover”, “16 in cover” and “12 × 20 lumbar” fill in common sizes for you. You can then change any value.

An error appears if the cover size is zero or not a number, or if the sofa depth is not one of the four choices. A warning appears if any side of the cover is under 8 in or over 60 in, so check that you entered the right measurement.

How much bigger should a throw pillow insert be?

Most guides say the insert should be larger than the cover, so the cover fills out without gaps. The tool shows how much larger each guide suggests. Guide T, a decorating blog, and guide Z, a home goods maker, both suggest an insert 2 in larger than the cover. Guide H, a home blog, suggests one size larger, which for a 22 in cover means a 24 in insert.

Guide C, a pillow cover seller, suggests 1 to 4 in larger and gives a chart. Its square chart maps a 20 in cover to a 22 in insert and a 24 in cover to a 26 or 28 in insert. For a square size that is not in the chart, the tool shows C’s rule of 1 to 4 in larger. For a 13 in cover, that means 14 to 17 in.

Guide P, a bedding maker, suggests 1 to 2 in larger. Its lumbar rule is 1 in larger for a snug fit. Guide T says nothing for covers under 18 in except the 16 in case, so the tool prints “does not say” for those sizes. For covers under 16 in the tool also warns that the 2 in rule mainly applies to covers of 18 in or more.

For a 20 in square cover, guides T, Z, C and H all say 22 in, and guide P says 21 to 22 in. The range across the guides is 21 to 22 in. For a 16 in cover, the range is wider, from 16 to 18 in, because guide T says 16 to 17 in and guide Z says 18 in.

Why do the pillow sizes for a sofa change with its depth?

The sofa sizes come from guide H. On a standard sofa, it suggests back pillows of 22 to 24 in. On a deeper sofa, the back pillows are 26 in, and on a shallower sofa they are 20 in. The front pillows step down by about 2 in per layer. For a standard sofa, the tool prints “Back pillows 22–24 in; front pillows 22 to 20 in”. For a deep sofa, it prints 26 in back and 24 to 22 in front. For a shallow sofa, it prints 20 in back and 18 to 16 in front.

Rectangular covers work differently. Only guide C’s lumbar chart and guide P’s lumbar rule give a size. A 12 x 20 in cover takes a 12 x 22 in insert in C’s chart, and a 14 x 24 in cover takes 16 x 26 in. If a rectangle is not in the chart, the tool says so and shows C’s 1 to 4 in rule and P’s “1 in larger for a snug fit”.

Some guides note that a very full insert may not need sizing up, and some covers are made exactly to size. The guides also disagree, so the tool says to check what your cover seller recommends.

Sources (checked 19 October 2026): Tidbits & Twine, throw pillow sizes · The Citizenry, choosing a pillow insert size · Chloe & Olive, pillow insert size guide · Puffy, pillow insert vs cover size · My Homier Home, throw pillow sizes

Worked examples

Calculated by the tool above; open it with the same values to see each step.

Frequently asked questions

What insert size do I need for a 20 inch throw pillow cover?

For a 20 in square cover, four guides say 22 in and guide P says 21 to 22 in. The tool’s range across the guides is 21 to 22 in. Check your cover seller’s advice before you buy.

Does the tool show one correct size?

No. It shows each guide’s suggestion and the range across them. Results are calculated from your inputs and typical sizes from the named sources, so the guides can differ.

Can I use the tool for a rectangular cover?

Yes, but only some guides give a rectangular size. The tool uses guide C’s lumbar chart and guide P’s lumbar rule. If your size is not in the chart, the tool tells you and shows the general rules.

What do the sofa pillow sizes mean?

They are suggested sizes for pillows along the back and front of a sofa, based on the sofa’s seat depth. Choose “Shallow sofa”, “Standard sofa” or “Deep sofa” to see them. Choose “Skip the sofa sizes” to hide them.

Does this tool work for bed pillows?

No. The page is for decorative throw pillows and covers, not bed pillows.

Why does the tool show a warning?

A warning appears if any side of the cover is under 8 in or over 60 in. This usually means a measurement needs checking, so measure the cover again.

Related tools

• Standard Sofa Dimensions: use it to check the seat depth and length of a sofa before you choose pillows.
• Coffee Table Dimensions: use it when you plan the table in front of your sofa.
• Living Room Rug Size: use it to find a rug size that suits your seating area.
• Wall Art Size Guide: use it to size artwork to hang above your sofa.
• Sofa, Mirror and Wall Decor Sizes: use it to plan mirrors and other wall decor around your sofa.