Cushion Cover Sizes: How to Make a Sofa Look Right

Posted by

August 12, 2026

On August 12, 2026

Short answer: buy the cover to match your existing cushion pad, then buy the pad one to two inches larger than the cover. An 18-inch cover on an 18-inch pad looks flat and half-filled; the same cover on a 20-inch pad looks full and expensive. That single detail changes a room more than the fabric does.

The five cushion sizes, and where each belongs

16 x 16 inches

Small accent cushions. Right on armchairs, on the front layer of a stacked group, and on a bed as the smallest of three. Too small to be the only cushion on a sofa — it looks lost.

18 x 18 inches

The default, and the size most cushions in most homes already are. If you are buying covers for pads you already own and cannot measure them, this is the safe assumption.

20 x 20 inches

For deeper sofas, where an 18-inch cushion disappears into the back and gives no support. If your sofa seat is more than about 60cm deep, start here rather than at 18.

24 x 24 inches

Floor cushions and the back layer on a large sectional. One 24-inch cushion at each end anchors a big sofa in a way three small ones never will.

12 x 20 inches (lumbar)

The one that does actual work. A lumbar cushion supports the lower back rather than decorating, which is why it belongs on the sofa you actually sit on, placed off-centre where your back meets the seat.

How to measure a cushion you already own

Take the pad out of its cover, lay it flat, and measure seam to seam across the middle — not corner to corner, and not with the pad standing up. Round to the nearest inch. Cushion pads compress over years, so an old 18-inch pad may measure closer to 17; buy the cover for the size it was, not the size it has sagged to, and replace the pad.

The insert rule, which most people get wrong

Cushion covers are made to the stated size. Cushion pads are soft. If you put an 18-inch pad in an 18-inch cover, the corners have nothing to fill them and the cushion looks like a deflated envelope — which is what most sagging cushions actually are, rather than a fabric problem.

Buy the pad one to two inches larger than the cover. An 18-inch cover wants a 20-inch pad. It takes a firm push to get it in, and that resistance is the point: it fills the corners, holds a plump shape and lets the cushion be karate-chopped or left square as you prefer.

Feather and down pads look best and need re-plumping daily. Polyester pads hold their shape without attention but flatten permanently after a few years. Feather-and-fibre blends sit between the two and are the practical choice for a sofa in daily use.

Arranging cushions so a sofa does not look staged

Odd numbers read as natural; even numbers read as showroom. On a three-seat sofa, five is the reliable arrangement: a pair of large cushions at each end, and one lumbar placed off-centre. On a two-seat sofa, three. On an armchair, one.

Mix one print with two plains rather than three prints, and repeat a colour from the print in the plains so the group reads as deliberate rather than accumulated. Vary the texture more than the colour — a linen, a cotton and a woven in the same palette look considered; three different colours in the same fabric look like leftovers.

The most common mistake is too many cushions. If sitting down requires moving cushions first, there are too many, and the room will read as a shop display rather than somewhere anyone lives.

Fabrics, and how they behave

Cotton — breathable, easy to wash, the most forgiving in a hot room. Best for the cushions that get sat against.
Printed linen — a looser weave with a natural slub and more texture. It creases, which is part of the look rather than a fault.
Blends — hold colour longer and crease less, at the cost of a slightly flatter surface.
Velvet — the most formal, and the one that shows every mark and every cat.

All of them fade in direct sun. In a room with a west-facing window, keep the strongly coloured covers off the cushion that sits in the afternoon light, or rotate the cushions every few months so they fade evenly rather than obviously.

Changing covers instead of cushions

This is the argument for buying covers rather than whole cushions. A set of covers stores flat in a drawer and costs a fraction of new cushions, so a living room can be changed twice a year — lighter cottons for summer, heavier textures for winter — for very little. Keep one set of pads and rotate the covers around them.

Wash new covers before first use to soften the weave and set the print. After that, machine-wash cool with like colours, turn them inside out, close the zip first, and dry in shade rather than direct sun.

Frequently asked questions

What size cushion cover do I need?

Measure an existing cover flat, seam to seam across the middle, and buy that size. 18 x 18 inches is the most common. Then buy the pad one to two inches larger than the cover so the cushion looks full rather than flat.

Should the cushion insert be bigger than the cover?

Yes, by one to two inches. This is the single most important detail in how a cushion looks. A same-size pad leaves the corners empty and the cushion reads as sagging no matter how good the fabric is.

Do cushion covers come with inserts?

Usually not, and that is what makes them an inexpensive way to change a room. Check the product page — where a listing is covers only, use the pads you already own, sized up.

How many cushions should a sofa have?

Odd numbers look more natural. Five works on a three-seat sofa: a pair of large cushions at each end and one lumbar placed off-centre. Three works on a two-seater. If you have to move cushions to sit down, there are too many.

Can cushion covers be machine washed?

Yes — cool, with like colours, no bleach. Turn them inside out and close any zip before washing, and dry in shade. Direct sun fades printed cotton and linen far faster than washing does.

What is a lumbar cushion for?

Supporting the lower back rather than decorating. At roughly 12 x 20 inches it sits in the curve of the spine when you lean back, which is why it belongs on the sofa you actually use rather than the one guests look at.

How do I stop my cushions looking flat?

Nine times out of ten the pad is the same size as the cover, or the pad is old polyester that has compressed. Replace the pad with one two inches larger. Feather and feather-blend pads also need re-plumping, which takes about ten seconds a day.

Where to buy cushion covers in Kuwait

KlippiK stocks cushion covers in 16, 18, 20 and 24 inch squares and 12 x 20 inch lumbar, in cotton and printed linen from Yellow Dwelling and Them. The wider living range covers throws and table linen, and bedroom textiles carries bedsheets and pillow covers in matching colourways.

Delivery across Kuwait is KWD 1.250 and free over KWD 30.000, dispatched within one business day for in-stock items, with cash on delivery available and 14 days to return anything unused in its original packaging.