Replace sofa cushions.

Sofa seat cushion replacement in the UK typically costs £60–£250 per cushion, depending on size, foam grade and whether the cover is being replaced or just the filling. For a typical 3-seat sofa, replacing all seat cushions runs £200–£600 total — far cheaper than a new sofa, and often what's needed when the rest of the frame is fine but the cushions have collapsed.

Cushions wear out in 5–10 years on most sofas. The seat takes 80% of the daily load, so it's the seat cushions that fail first while the back and arms remain fine. Replacement is easier than people assume.

Typical UK costs

Diagnosing cushion problems

• Feels flat / sinks — foam has lost recovery. Most common; fix is new foam.
• Lumpy or uneven — typically fibre/feather fill that's clumped. Either re-fluff (temporary) or replace with foam-core construction.
• Cushion shifts forwards — likely fabric stretch or cover too loose; covers may need re-zipping or cushion shape changing.
• One side higher than other — uneven wear. Replace both cushions, even if only one is bad — they age differently after that.
• Cover sagging or torn — the cover itself needs replacing; foam inside may be fine.

Foam densities — picking the right one

Foam grade is specified by density (kg/m³) and firmness. The two move somewhat independently but density drives lifespan more than firmness:

• Standard density (24-30 kg/m³) — budget. 5-7 year lifespan. Fine for occasional use.
• High-density (35-40 kg/m³) — typical for premium UK sofas. 8-12 year lifespan. Best balance for most homes.
• Reflex / latex / pocket-spring core — premium feel, longest lifespan (10-15+ years). 30-50% more expensive.
• Feather and down wrap over foam core — luxury feel, requires periodic re-plumping. Best for occasional-use formal living rooms.

How replacement works

For a typical UK sofa with zipped cushions:

1. Unzip the cover and remove old foam.
2. Measure the cushion (width × depth × height) — old foam often shrinks; measure the cover from the inside.
3. Choose foam grade based on use case.
4. New foam cut to size by a foam supplier or sofa specialist.
5. Wrap foam in dacron / polyester fibre for softer feel and to prevent the cover sagging.
6. Insert into cover, zip up.

Many specialists offer a measuring + supply + fit service for £60–£140 per cushion. DIY foam kits (online suppliers like FoamForYou or Direct Foam) are cheaper but require careful measurement.

Things people often miss

• Replace all seat cushions together — even if only one is bad. New foam alongside aged foam looks and feels noticeably different.
• Check back cushions while you're there — back cushions wear more slowly but often need re-fluffing or new fillings every 10-15 years.
• Frame inspection — a sagging seat can be a sagging frame, not just foam. Lift the cushions, push down on the deck below — if it gives more than 1-2 cm under hand pressure, the frame webbing may have failed.
• Cushion zip quality — cheap zips fail before the foam does. Worth upgrading to a heavy-duty YKK zip when re-covering.
• Fire labels — UK Furniture and Furnishings (Fire Safety) Regulations 1988 require fire-retardant fillings. Reputable foam suppliers comply by default; check labels match if you're worried about insurance.

Frequently asked questions

Want a local pro to handle this? A sofa cushion specialist or upholsterer will measure, source the right foam grade, and fit cleanly. The £200-£600 spend on a 3-seat refresh is the highest-leverage furniture repair you can do — gets a sagging sofa feeling new again at a fraction of replacement cost.