A topper sits on the mattress and changes what the surface feels like. It does not change what the mattress does underneath, and that single distinction answers most of the questions people have before buying one.
What a topper fixes
- A mattress that is too firm. This is the thing a topper is genuinely good at.
- A surface that has stopped feeling comfortable while the support underneath is still sound.
- A bed you cannot replace yet — a rented flat, a guest room, a let.
What it cannot fix
A dip. If the mattress has gone soft in the middle, a topper lies in the dip with you — it follows the shape rather than filling it. It also will not rescue a mattress whose springs have gone, and it will not make a too-soft bed firmer: there is no such thing as a firming topper, only a thinner one.
Depth
Depth is the whole decision. Two to four centimetres softens a mattress that is close to right. Five to eight is a real change in feel, and it is what you want if the mattress is noticeably too hard. Deeper than that and you are effectively buying a thin mattress.
Whatever you choose, add it to the mattress depth and buy your fitted sheet to the total. A 25 cm mattress with a 5 cm topper needs a 30 cm pocket — see how to choose bedsheets.
Fill
Memory foam moulds to you and holds heat; it is the choice for pressure relief, and the one to think twice about if you sleep hot. Gel-infused and bamboo-covered versions exist precisely to address that.
Microfibre is lighter, cooler and springier. It is the hotel-feel option — soft on top without the sink of foam — and it is washable in a way foam is not.
Foam needs to air for a day or two out of the packaging before it is slept on, and it is never machine washed: the cover comes off, the foam is spot-cleaned and dried flat.
One topper, or one per side?
If two people disagree about firmness, two single toppers on a king or super king is a far better answer than a compromise in the middle. It is also how most hotels handle a bed that has to suit everyone.
Our mattress toppers list their depth in the name, and the deeper ones are listed with the sheet depth they need. If a topper is going onto a bed that is let, put a protector over the top of it — the topper is now the expensive layer.
