A mattress topper is a removable padded layer that sits on top of a mattress to change how it feels. The two common thicknesses are 5 cm and 10 cm: a 5 cm topper softens a mattress that's in decent shape, and a 10 cm topper changes the feel of the whole bed. This guide compares the two and explains which fitted sheet you need.
Here's how the two thicknesses compare:
| 5 cm topper | 10 cm topper | |
|---|---|---|
| Best for | A mattress that's firm but supportive | A mattress with dips, lumps or a very hard surface |
| How it feels | A softer top layer, same bed underneath | A noticeably deeper, plusher bed |
| Height added | About 5 cm | About 10 cm |
| Fitted sheet | Standard sheets usually still fit | Needs an extra deep sheet |
| Sizes we make | Single, Double, King, Super King | Single, Small Double, Double, King, Super King |
Is a 5 cm mattress topper thick enough?
Yes, a 5 cm mattress topper is thick enough if your mattress is supportive but feels too firm. It adds a soft layer on top without changing how the bed holds you. It won't hide a sagging middle or a broken spring, because 5 cm of filling compresses under body weight.
Think of 5 cm as a comfort upgrade. It's also the right choice for guest beds and children's beds, where you want a softer surface and don't want the bed to get much higher.
Is a 10 cm topper too thick?
No, a 10 cm topper isn't too thick for most beds, but it does add real height. It's the right choice when a mattress has dips, lumps or a surface so hard it causes pressure on hips and shoulders. The trade-off is that the bed sits 10 cm higher and needs a deeper fitted sheet.
Two situations make 10 cm the wrong pick. If your mattress is already soft, a thick topper makes it softer still and your hips will sink. And if the mattress is sagging badly in the middle, a topper fills the dip for a while but won't fix the support underneath it.
Our 5 cm and 10 cm mattress topper has a quilted microfibre filling sewn into sections, so it can't drift into one end of the bed. Elasticated straps on each corner hold it flat, and it machine washes at 30 to 40°C.
Will a fitted sheet go over a 10 cm topper?
A standard fitted sheet usually won't go over a 10 cm topper, because a typical mattress plus 10 cm is deeper than its pocket. Measure the mattress and topper together, then pick a sheet whose pocket is deeper than that total. A 40 cm pocket covers a mattress up to 30 cm deep with a 10 cm topper.
Here's how to check in 3 steps:
- Measure your mattress from its top surface to its bottom edge.
- Add the topper thickness: 5 cm or 10 cm.
- Choose a fitted sheet with a pocket a few centimetres deeper than the total, so the elastic tucks underneath.
Our extra deep fitted sheet has a 40 cm pocket with elastic all the way round, made to go over our toppers without popping off at the corners. It comes in Single, Double, King and Super King, in 6 colours.
Not sure what size your bed is? Our chart of UK bed sizes in cm lists every mattress from small single to emperor. And for where the topper sits in relation to the protector and sheet, see the correct order of bedding layers.
Written by the Adam Home team at Ensor Mill, Rochdale.
