Fitted Sheet Sizes UK: Size & Depth Guide
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Choosing a fitted sheet should be simple, but mattress size is only half of the equation. You also need to consider the depth of your mattress and whether a mattress topper adds extra height.
In this UK fitted sheet size guide, we explain the most common Single, Double, King and Super King mattress dimensions, how fitted sheet depth works, how to measure your mattress and the difference between 30cm deep and 40cm extra deep fitted sheets.
If you already know the size and depth you need, explore our complete fitted sheets range.
UK Fitted Sheet Size Guide
A fitted sheet needs to correspond with the width and length of your mattress while also providing enough depth to sit comfortably around the sides.
The table below shows the approximate mattress dimensions commonly used for popular UK bed sizes.
| UK Bed Size | Approx. Mattress Width | Approx. Mattress Length | Common Mattress Size |
|---|---|---|---|
| Single | 90cm | 190cm | 90 x 190cm |
| Double | 135cm | 190cm | 135 x 190cm |
| King | 150cm | 200cm | 150 x 200cm |
| Super King | 180cm | 200cm | 180 x 200cm |
Important: These are common UK mattress dimensions rather than a guarantee for every mattress. Manufacturing tolerances, specialist beds and imported mattresses can vary, so always measure your own mattress before ordering.
What Size Fitted Sheet Do I Need?
Start by matching the fitted sheet to your mattress rather than simply relying on the name of your bed.
If your mattress is approximately 135 x 190cm, for example, you would normally look for a Double fitted sheet. A mattress around 150 x 200cm would normally require a King size fitted sheet.
There are three measurements to check:
- Width – from one side of the mattress to the other.
- Length – from the head of the mattress to the foot.
- Depth – vertically from the top sleeping surface to the bottom edge.
The third measurement is easy to overlook, but it can make a significant difference to how comfortably a fitted sheet sits around your mattress.
Single Fitted Sheet Size UK
A standard UK Single mattress is commonly around 90 x 190cm.
When buying a Single fitted sheet, check both the mattress dimensions and the pocket depth. Two Single mattresses can have the same width and length while being very different in thickness.
This is particularly relevant if your mattress includes deep comfort layers or if you use a mattress topper.
Double Fitted Sheet Size UK
A standard UK Double mattress is commonly around 135 x 190cm.
Some fitted sheets are manufactured slightly larger than the nominal mattress dimensions to provide the required fit around the mattress, so always compare the measurements shown on the individual product page.
Depth also matters. A Double mattress requiring a 30cm pocket should not automatically be paired with a much deeper sheet simply because both products are labelled Double.
King Size Fitted Sheet Size UK
A standard UK King mattress is commonly around 150 x 200cm.
King mattresses are longer than standard UK Double mattresses, so using the correct size is important as well as selecting the correct depth.
If you have a deeper King mattress, you can explore our extra deep fitted sheets, including 40cm options designed for mattresses requiring additional side coverage.
Super King Fitted Sheet Size UK
A standard UK Super King mattress is commonly around 180 x 200cm.
As with the other sizes, measure your mattress before ordering rather than assuming every Super King mattress has exactly the same dimensions or depth.
Pay particular attention to mattress depth if you have a substantial topper or a thicker mattress construction.
What Does Fitted Sheet Depth Mean?
Fitted sheet depth refers to the amount of fabric available to extend down the side of the mattress.
You may also see this described as the pocket depth.
For example:
- A 30cm deep fitted sheet has approximately 30cm of fitted depth.
- A 40cm deep fitted sheet has approximately 40cm of fitted depth.
The depth measurement is separate from the width and length of the sheet.
This means two King fitted sheets can have the same overall mattress width and length but different pocket depths.
What Is a Standard Fitted Sheet Depth?
There is no single pocket depth that every manufacturer or retailer uses as a universal standard.
Mattresses also vary considerably in thickness, which is why checking the stated fitted depth is more useful than relying on terms such as “standard”, “deep” or “extra deep” alone.
At Stoftly, our fitted-sheet range includes 30cm deep and 40cm extra deep options, allowing you to choose according to your mattress measurement.
30cm Deep Fitted Sheets
A 30cm deep fitted sheet provides approximately 12 inches of pocket depth and can be a useful option when a shallower sheet does not provide enough coverage around your mattress.
Before choosing 30cm, measure your mattress rather than assuming that every deeper mattress requires the same pocket size.
Our 30cm deep fitted sheets are available in different thread count specifications, colours and UK bed sizes.
40cm Extra Deep Fitted Sheets
A 40cm deep fitted sheet provides approximately 16 inches of pocket depth and is designed for mattresses that require considerably more fabric around the sides.
This can be particularly useful for thicker mattresses or mattress-and-topper combinations, provided your total measured depth is appropriate for the sheet.
Browse our 40cm extra deep fitted sheets if your mattress requires the additional depth.
30cm vs 40cm Fitted Sheet: Which Should You Choose?
The deepest fitted sheet is not automatically the best fitted sheet.
The right choice depends on the actual depth of your mattress.
| Fitted Sheet | Approx. Pocket Depth | Consider When |
|---|---|---|
| 30cm Deep | 30cm / approx. 12 inches | Your mattress needs more coverage than a shallower sheet but does not require a 40cm pocket. |
| 40cm Extra Deep | 40cm / approx. 16 inches | Your mattress or mattress-and-topper combination requires a more generous fitted depth. |
A sheet that is too shallow may struggle to provide enough coverage around the mattress. A sheet that is unnecessarily deep may leave more loose fabric than you need.
Measuring first is therefore more reliable than automatically choosing the deepest option available.
How to Measure a Mattress for a Fitted Sheet
You only need a tape measure and a few minutes to check your mattress properly.
1. Measure the Width
Measure straight across the mattress from one side to the other at its widest point.
2. Measure the Length
Measure from the top edge of the mattress to the bottom edge.
3. Measure the Mattress Depth
Measure vertically from the top sleeping surface of the mattress down to the bottom edge.
Do not measure around the mattress or follow the curve of the fabric. You want the vertical height.
4. Include Your Mattress Topper
If a mattress topper stays permanently on your bed underneath the fitted sheet, include its height in your measurement.
For example, if your mattress is 25cm deep and your topper adds another 5cm, the fitted sheet needs to accommodate approximately 30cm of combined depth.
5. Check the Product Measurements
Finally, compare your measurements with the size and fitted depth shown on the individual product page.
This is particularly important because dimensions can vary slightly between products and manufacturers.
Do I Need a Deeper Fitted Sheet with a Mattress Topper?
Possibly. What matters is the combined depth of everything that will sit underneath the fitted sheet.
If your mattress measures 24cm and your topper adds 6cm, for example, you are working with approximately 30cm of total height.
Measure the mattress and topper together while the topper is in its normal position on the bed.
If you are still deciding how much topper depth to add, read our 5cm vs 10cm mattress topper guide to compare the added height, cushioning and fitted sheet implications of each option.
You can then compare that measurement with the pocket depth of the fitted sheet you are considering.
Why Does My Fitted Sheet Keep Coming Off?
Several factors can cause a fitted sheet to move or come away from the corners.
The sheet may be too small for the mattress width or length, the pocket may not provide enough depth, or a mattress topper may have increased the overall height beyond what the sheet comfortably accommodates.
Incorrect sizing is not the only possible cause, but checking all three mattress measurements is a useful place to start.
Should a Fitted Sheet Be the Same Size as the Mattress?
Choose the fitted-sheet size intended for your mattress category, but compare the actual product dimensions rather than expecting the finished sheet measurements to be identical to the mattress measurements.
Fitted sheets are constructed to wrap around the mattress, and individual products can therefore have slightly different finished dimensions.
The most useful approach is to check the manufacturer's stated bed size, width, length and pocket depth against your own mattress.
What About a Fitted Valance Sheet?
A fitted valance sheet is slightly different because it combines a fitted section around the mattress with a decorative fabric drop around the sides of the bed.
For example, our Pintuck Fitted Valance Sheet has a 25cm fitted mattress box together with a separate 40cm decorative valance drop.
The 40cm measurement in this case refers to the valance drop, not the mattress depth. This is different from a 40cm extra deep fitted sheet, where 40cm describes the fitted pocket itself.
Choosing the Right Fitted Sheet
The easiest way to choose is to work in this order:
- Identify your mattress size.
- Measure its actual width and length.
- Measure its depth.
- Add the depth of any topper that stays beneath the sheet.
- Compare those measurements with the fitted-sheet product specification.
Once you know those measurements, choosing between Single, Double, King or Super King and between a 30cm or 40cm pocket becomes much easier.
Explore our full fitted sheets collection, or go directly to our 30cm deep fitted sheets and 40cm extra deep fitted sheets.
Fitted Sheet Size & Depth FAQs
What size fitted sheet do I need?
Measure the width and length of your mattress and match them to the appropriate UK bed size. Then measure the mattress depth to make sure the fitted pocket provides enough coverage.
What depth fitted sheet do I need?
Measure vertically from the top surface of your mattress to the bottom edge. Include a mattress topper if it will remain underneath the sheet, then compare the combined measurement with the stated fitted-sheet depth.
What is the standard fitted sheet depth in the UK?
There is no single universal pocket depth used by every manufacturer. Check the actual depth stated on the product rather than relying only on labels such as standard, deep or extra deep.
What is the size of a UK Single fitted sheet?
A standard UK Single mattress is commonly around 90 x 190cm. Check the specific fitted-sheet dimensions and pocket depth before ordering.
What is the size of a UK Double fitted sheet?
A standard UK Double mattress is commonly around 135 x 190cm. Mattress depth varies, so measure it separately when choosing your fitted sheet.
What is the size of a UK King fitted sheet?
A standard UK King mattress is commonly around 150 x 200cm. Always compare your mattress measurements with the specifications of the fitted sheet you are buying.
What is the size of a UK Super King fitted sheet?
A standard UK Super King mattress is commonly around 180 x 200cm. You will also need to check the mattress depth to choose the right fitted pocket.
Is a 30cm fitted sheet deep?
A 30cm fitted sheet provides approximately 12 inches of pocket depth and is designed for mattresses requiring more coverage than a shallower fitted sheet.
Is a 40cm fitted sheet extra deep?
A 40cm fitted sheet provides approximately 16 inches of pocket depth and is intended for mattresses requiring a more generous fitted depth.
Should I buy a 30cm or 40cm fitted sheet?
Choose according to your measured mattress depth rather than automatically choosing the deeper option. If you use a mattress topper, include it in the total depth measurement.
Do I measure a mattress topper when choosing a fitted sheet?
Yes, if the topper will stay on the mattress underneath the fitted sheet. Measure the mattress and topper together to determine the total depth the sheet needs to cover.