What Depth Fitted Sheet Do I Need? A Simple UK Guide

Most UK mattresses measure between 20 and 30 cm deep, so a fitted sheet rated to around 30 cm will cover the majority of beds. If you sleep on a pillow top, a hybrid, or a mattress with a topper on it, you will usually need a deep fitted sheet rated to 35 cm or more. Every Bedable fitted sheet is made to fit mattresses up to 36 cm deep.

The only way to be certain is to measure. It takes under a minute, and it is the difference between a sheet that stays put and one that pings off the corner at three in the morning.

The short answer

• Standard mattress, no topper: a sheet rated to 25 to 30 cm is usually enough.
• Pillow top, hybrid, or any mattress with a topper: choose a deep fitted sheet, 35 cm or more.
• Not sure: measure the mattress, then allow about 2 cm of margin.
• Bedable fitted sheets: made for mattresses up to 36 cm deep, in Single, Double, King and Super King.

How to measure your mattress depth

You need a tape measure and about thirty seconds. Measure the mattress only. Do not include the divan base or the bed frame, because a fitted sheet never wraps around those.

1. Strip the bed. Take the old fitted sheet off first, so you are measuring the mattress itself and not fabric bunched on top of it.
2. Measure the side, top to bottom. Hold the tape flat against the side of the mattress, halfway along the long edge. Run it from the top surface down to the point where the mattress meets the base.
3. Put your topper back on. If you use a mattress topper, measure again with it in place. The sheet has to stretch over both.
4. Allow about 2 cm. A small margin lets the elastic tuck properly underneath instead of straining at the corners.

Measure halfway along the edge rather than at a corner. Corners compress, and they will give you a reading a centimetre or two short.

How deep is a standard UK mattress?

There is no single UK standard for mattress depth, which is exactly why so many people end up with the wrong sheet. Depth comes from how the mattress is built, not from the bed size. A Single and a Super King from the same range are usually the same depth as each other.

Those are typical ranges rather than rules, so treat them as a sanity check on your own measurement, not a substitute for it.

What a 36 cm fitted sheet actually fits

Our fitted sheets are cut for mattresses up to 36 cm deep, with a deep, extra-grip elasticated hem that holds the sheet under the mattress rather than perched on the edge of it.

In practice that one depth covers almost every bed: a 25 cm pocket sprung mattress, a 30 cm hybrid, or a 28 cm mattress with a 6 cm topper on top of it.

Sateen fitted sheets come in all four sizes. Percale fitted sheets are available in Double, King and Super King.

If your mattress measures more than 36 cm once the topper is on, these are not the right sheets for your bed, and we would rather say so now than have you post them back to us.

Do not forget the topper

This is the single most common reason a fitted sheet does not fit. A memory foam or feather topper adds anywhere from 5 to 10 cm, which quietly turns a 28 cm mattress into a 36 cm one. Always measure with the topper in place.

The same goes for a quilted mattress protector, although those are usually thin enough to ignore.

Why fitted sheets work loose in the night

If your sheet keeps coming off, depth is usually the reason, but not the only one.

• The sheet is too shallow. There is not enough fabric to reach underneath, so the elastic sits on the edge of the mattress and the first turn in the night pulls it off.
• The sheet is too deep. An oversized sheet has slack it cannot use, so it wrinkles across the bed instead of holding tension.
• Elastic in the corners only. Cheaper sheets gather at the four corners and leave the sides loose. A hem elasticated all the way round holds far better.
• The fabric has no structure. A tightly woven cotton keeps its shape wash after wash instead of gradually stretching out.

Sateen or percale?

Once the depth is right, the rest is about how you like a bed to feel.

Sateen fitted sheets are woven at a 460 thread count for a smooth, silky surface with a subtle sheen, and start at £45. Percale fitted sheets are cool, matte and crisp, closer to a hotel sheet, and start at £70. Both are 100% long-staple cotton, both are OEKO-TEX certified, and both fit mattresses up to 36 cm.

If you are torn between the two, our guide to percale or sateen bedding sets out the difference. And if you are still deciding whether you need a fitted sheet at all, we have compared flat sheets and fitted sheets too.

Frequently asked questions

What is the standard fitted sheet depth in the UK?

Most standard UK fitted sheets are made for mattresses around 25 to 30 cm deep. Anything sold as a deep fitted sheet usually starts at about 35 cm. Bedable fitted sheets fit mattresses up to 36 cm.

Can a fitted sheet be too deep?

Yes. A sheet cut much deeper than your mattress carries spare fabric that never pulls taut, so it wrinkles across the surface and works loose. Matching the depth to within a few centimetres gives the best result.

Do I measure the mattress or the whole bed?

The mattress only. Measure from the top surface down to the point where the mattress meets the divan or frame. The base is never covered by the fitted sheet.

Does a mattress topper change the depth I need?

Almost always. Toppers add roughly 5 to 10 cm, so measure with the topper in place and buy for that combined depth.

What depth are Bedable fitted sheets?

All of them fit mattresses up to 36 cm deep, in Single, Double, King and Super King, with a deep elasticated hem.

Is 35cm deep for a fitted sheet?

Yes, 35 cm is deep for a fitted sheet. Labels vary, but as a rough guide a 28 cm pocket is standard, 32 cm is generous, and anything from about 35 cm counts as deep. Bedable's fitted sheets suit a total depth of up to 36 cm, topper included, so a 35 cm mattress fits. For anything deeper, look for a 40 cm pocket and elastic all the way round.

What depth fitted sheet do I need on a 25cm mattress?

For a 25 cm mattress, choose a standard fitted sheet with a pocket of around 28 to 30 cm. Those few extra centimetres let the elastic wrap underneath and hold. Got a topper? Add its thickness first, because a 25 cm mattress with a 5 cm topper already measures 30 cm and needs a deeper sheet. Width and length simply follow your bed size; the 25 cm only decides the depth.

Does a fitted sheet need to be bigger than the mattress?

Yes, but only in depth. Width and length should match the mattress, while the pocket should be a few cm deeper than the mattress plus any topper, so the elastic tucks under. That margin also allows for the slight shrinkage cotton can show after hot washes or tumble drying. Sizing up doesn't help: a king sheet on a double leaves 15 cm of loose width and 10 cm of spare length.

What is the deepest fitted sheet I can get?

The deepest fitted sheets you'll commonly find in the UK are around 40 cm, and some specialist ranges reach 45 or 50 cm for very deep mattresses with thick toppers. Beyond that, a made to measure sheet is usually the only answer. At these depths, pick a sheet with elastic all the way round the hem, not just at the corners, and consider sheet straps underneath to stop the corners lifting overnight.

What is the average size of a fitted sheet?

There's no single average size, because each fitted sheet is made for a specific UK bed size. Single sheets measure 90x190 cm, doubles 135x190 cm, kings 150x200 cm and super kings 180x200 cm, with pocket depth chosen separately to suit the mattress. European beds usually run 200 cm long, so a 140x200 cm continental double needs its own sheet.

Measure once, buy once

Take the thirty seconds now and you will not be wrestling with a sheet at bedtime. Browse our fitted sheets, or start with the Essentials Bedding Set if you would rather have the duvet cover, fitted sheet and pillowcases together.

Free UK delivery, free returns and a 365-day guarantee on everything, so if the fit is not right, you are not stuck with it.