Take an inner cushion 2 to 5 cm larger than the cover in both directions. A 45 by 45 cm cover wants a 47 to 50 cm filler. Match the sizes exactly and you get the flat, half-empty look with collapsed corners that makes a good cover seem cheap.
Why oversizing works
A cushion cover is a fixed box, and filling sits loosest at the corners because that is where it has furthest to travel. A slightly larger inner cushion is compressed by the cover, which pushes filling outwards and keeps the corners packed. It also means the cushion still looks full after a year, when the filling has settled a little.
| Cover size | Inner cushion |
|---|---|
| 40 x 40 cm | 42-45 cm |
| 45 x 45 cm | 47-50 cm |
| 50 x 50 cm | 52-55 cm |
| 60 x 60 cm | 62-65 cm |
| 30 x 50 cm (lumbar) | 32 x 52 cm |
Down or synthetic
Down is softer, moulds to your back and has that characteristic slump when you lean into it. It needs plumping to look its best, which suits some people and irritates others. Synthetic filling springs back more firmly, keeps its shape without attention, and is the sensible choice if anyone in the house has a dust mite allergy. Neither is better in the abstract; they behave differently and you should pick the behaviour you want.
How many, and in what sizes
Three to five cushions on a three-seater looks full without becoming a pile you have to move before sitting down. The arrangement that works most reliably: two larger cushions at the outer ends, one or two mid-size, and a single lumbar cushion as the odd one out. Vary the texture more than the colour - a woven, a smooth and a ribbed cover in the same colour family reads richer than five different colours in the same fabric.
Washing without ruining anything
Most cushion covers take 30 degrees on a delicate programme, but linen and wool ask for separate treatment, so read the care label before the first wash rather than after. Natural fibres can shrink a few percent, which is another argument for an oversized filler: a cover that shrinks slightly onto a larger inner cushion still looks right.
Many synthetic inner cushions can be washed at 30 degrees too. The step people skip is drying them completely - a filling that feels dry on the outside can still hold moisture in the core, and that is how a cushion starts to smell.
When to replace a filling
With daily use, three to five years is normal. The test is simple: plump it, put it down, and watch. If it stays plump for a few minutes it is fine. If it collapses immediately, the fibres have lost their spring and no amount of plumping will bring it back. Replacing the filling rather than the whole cushion is the cheaper fix and usually the one people forget is available.
Turn and plump your cushions regularly, and rotate which one sits where. A cushion that always lies in the same spot under the same shoulder sags on one side, and by the time you notice, it is permanent. The same applies to the seat itself - see our seating and sofas for how upholstery holds up over time.
By Meike van Dongen · Veem, Amsterdam · 18 August 2026