Buying a new bed, a fresh set of sheets, or simply trying to work out whether your bed will fit in a different room, whatever the reason, getting the measurements right saves you a wasted trip, a failed return, and a lot of frustration. The good news is that measuring a bed is straightforward. You do not need any special tools or skills. With a metal tape measure and a notepad, the whole job takes under ten minutes.
This guide walks you through every measurement you need, in the order you need to take them.
What You Need Before You Start
Before you put the tape measure anywhere near the bed, get these ready:
- A metal tape measure (3–5 metres): Metal holds its shape and stays rigid across longer distances. A soft fabric tape sags in the middle and stretches over time, both of which will give you a number that is slightly off, and slightly off is enough to buy the wrong sheets or order the wrong mattress.
- A notepad and pencil: You will take up to six measurements. Do not try to hold them all in your head.
- A helper (optional): Useful for holding one end of the tape steady across the full length of a king or super king bed.
Once you have those, strip the duvet, pillows, and any mattress topper off the bed completely. Pull the bed a little away from the wall if you can, so you have access to all four sides.
How to Measure a Bed in 5 Simple Steps
Step 1: Measure the Bed Width
Place one end of the tape measure at the left edge of the mattress and pull it straight across to the right edge. Keep the tape flat against the surface and measure at the widest point, some mattresses bow out slightly in the middle, so measure there rather than at the very ends.
Write this number down in centimetres. This is your mattress width, and it is the single most important number for identifying your bed size.
Step 2: Measure the Bed Length
Run the tape from the top edge of the mattress, the head end, straight down to the bottom edge at the foot. Keep the tape parallel to the side of the mattress rather than letting it drift diagonally.
Write this number down. This is your mattress length. Together with the width, these two numbers will tell you exactly what size bed you have when you check them against the size chart below.
Step 3: Measure the Mattress Depth
This is the measurement most people skip, and it is the one that causes the most problems when buying bedding.
Stand the tape measure upright against the side of the mattress and measure from the very bottom edge to the top sleeping surface. Do not include any mattress topper in this measurement; you want the mattress alone.
Most UK mattresses sit somewhere between 20 cm and 30 cm deep. Standard fitted sheets are designed for exactly that range. If your mattress comes in deeper than 30 cm, which is common with memory foam, hybrid, and pillow-top mattresses, standard sheets will not stay tucked and will pop off the corners overnight. In that case, you need deep-pocket fitted sheets, which are specifically made for deeper mattresses.
Note: Write the depth down alongside your width and length.
Step 4: Measure the Bed Height
Bed height is not one single measurement, it is two numbers added together: Floor Clearance + Mattress Height.
- Measurement 1 – Floor clearance: Measure from the floor up to the top of the bed frame’s side rails or cross-slat bar. This is the base height, the solid structure the mattress sits on. Do not measure to the bottom of the side panels, as these often sit lower and will give you a misleading number.
- Measurement 2 – Mattress height: Stand the tape upright against the side of the mattress and measure from the bottom to the top surface. Most UK mattresses are between 20 cm and 30 cm tall.
Add the two together and you have your total bed height, the distance from the floor to the surface you actually sleep on.
This number matters more than people realise. A very high total height can be difficult for young children or elderly people to get in and out of safely. A very low bed can feel awkward to rise from if you have knee or back problems. If you are buying a new bed for a specific person, check the total height against the frame listing before you order.
Step 5: Measure the Full Bed Frame
The mattress and the frame are not the same size. The frame, which includes the side rails, headboard, and footboard, almost always extends beyond the mattress on all sides. If you only measure the mattress and use that figure to plan your room layout, the bed will take up more floor space than you expected.
To measure the frame, take four readings:
- Outside width, tape across from the outer edge of one side rail to the outer edge of the opposite rail, at the widest point.
- Outside length, tape from the very outer edge of the headboard to the very outer edge of the footboard.
- Frame height, floor to the top of the side rails.
- Headboard height, floor to the very top of the headboard, measured separately.
These frame dimensions are the ones to use when deciding whether the bed will fit in your room, whether it will pass through a doorway during delivery, and how much space you will have around it once it is in place.
What Size Is My Bed?
Once you have your mattress width and length, match them against the standard UK sizes below.
| Size | Width × Length (cm) | Width × Length (ft) |
| Small Single | 75 × 190 | 2’6″ × 6’3″ |
| Single | 90 × 190 | 3’0″ × 6’3″ |
| Small Double | 120 × 190 | 4’0″ × 6’3″ |
| Double | 135 × 190 | 4’6″ × 6’3″ |
| King | 150 × 200 | 5’0″ × 6’6″ |
| Super King | 180 × 200 | 6’0″ × 6’6″ |
If your measurements match one of these exactly, you have a standard UK size and buying bedding, mattresses, and accessories will be straightforward. If your numbers fall between two sizes, your bed may be non-standard, either an older bed made before sizing was standardised, or a bed from a brand that uses its own dimensions. In that case, ignore the size names entirely and shop by your actual centimetre measurements, comparing them directly against the product specifications on the listing.
Does Bed Style Affect How You Measure?
The steps above apply to every bed, but the style of the frame does affect how much extra space it takes up beyond the mattress. Here is what to expect from each type:
- Divan base: A divan sits almost flush with the mattress on all sides, so the frame footprint is very close to the mattress size. These are the easiest to measure and the least likely to surprise you with extra bulk.
- Wooden or metal frame: Most wooden and metal frames extend a few centimetres beyond the mattress on all sides due to the thickness of the side rails. Always measure the outer frame rather than assuming the mattress size tells the whole story.
- Upholstered bed: Upholstered frames, fabric or velvet covered, add padding around the sides and often have a substantial headboard. The outer frame can be noticeably wider and longer than the mattress inside it. Measure the outermost points.
- Sleigh bed: The curved headboard and footboard on a sleigh bed add extra length at both ends. These beds often feel larger in a room than their mattress size suggests. Measure end to end across the full curve.
- Ottoman and storage bed: The key extra measurement here is the opening clearance, how much space the lid needs above and in front of the bed when it lifts. If the bed sits close to a wall or wardrobe, check this before you buy.
In every case, always measure from the outermost edges of the frame when planning room layout.
Three Mistakes That Catch People Out
- Letting the tape sag: If the tape droops between your hands, it reads longer than the true straight-line distance. Pull it taut the entire length of the measurement.
- Only measuring the mattress: The mattress is always smaller than the frame. If you measure the mattress and use that to plan where the bed will sit in your room, you will underestimate the true footprint, sometimes by five to ten centimetres on each side.
- Trusting the label over your tape: UK bed frames carry a standard manufacturing tolerance of ±2 cm. This means a bed sold as a double may measure 133 cm wide rather than exactly 135 cm, or 137 cm rather than 135 cm. Both are within tolerance and considered correct. Your own tape measure reading is always more reliable than the size printed on the box.
Ready to Find the Right Bed?
You have your measurements, now the easy part begins. Browse the full range of Bed Frames, Ottoman Beds, Upholstered Beds, Daybeds, and Folding Beds at Aosom UK. Every listing includes the exact frame and mattress dimensions, so you can match your numbers with confidence and know your new bed will fit before it arrives.
FAQs
1. Should I measure the mattress or the frame?
It depends on what you are buying. Measure the mattress when buying bedding. Measure the inside of the frame, rail to rail, when buying a replacement mattress, so it drops in snugly without gaps. Measure the full outer frame when planning room layout or checking delivery access.
2. How do I measure headboard height?
Stand the tape at the floor and run it up to the very top of the headboard. This is a separate measurement from frame height and sleeping height. Headboard height matters if the bed will sit under a sloped ceiling, in an alcove, or beneath wall-mounted shelving.
3. What if my measurements do not match any standard size?
Shop by your centimetre measurements rather than a size name. Most bed and bedding listings show the exact dimensions on the product page. Match your numbers to those figures directly and ignore the size label entirely.