Whether you’re out shopping for a new carpet or browsing the vast selection of high-quality carpets available to buy online, it’s a good idea to know the dimensions for the room you’re buying for. This way, you can work out how much your new floorcovering is going to cost – you’ll be able to get the best quality carpet you can afford without going over budget.

Initial estimate

If you have a room that’s a regular shape – just a straightforward square or rectangle – working out the size of carpet you need is simple. Just measure the width and length of the room to work out the total number of square metres required.

Example: 3m x 5m = 15m2

You can then take the price of the carpet per square metre to work out approximately how much you’ll be spending:

Example: £10/m2 x 15 = £150

The fine details

Make sure you are measuring at the widest parts of the room. If you have any indents in the shape of the room, such as an alcove, fireplace or L-shaped section, measure these too, to make sure you’re making the best use of the carpet you buy It can be helpful to draw out a plan of the room (not necessarily to scale!) and mark your sizes on there.

You need to allow enough carpet to fit under the door threshold, and avoid any gaps between rooms. The are many different types of doors so be sure to measure to the back of the doorframe – typically this adds around 5-10cm onto the measurements for each room length that includes a doorway.

Remember to include a little extra on your measurements to allow for walls that may not be straight and seams where two lengths of carpet need to be joined. This gives you a margin for error – nobody wants to be left with a carpet that doesn’t meet the edges of the room!

Working out how much carpet to buy

Unfortunately, buying carpet isn’t always as simple as working out the size of the room and buying the equivalent square meterage of carpet. Most carpet typically comes in 4 metre wide rolls. This means that if your room is 3m x 5m as in the example above, you’ll actually need to buy a 4m x 5m carpet and there will be some wastage. For small rooms, you may find it more economical to buy a carpet offcut or remnant to fit your space.

If your room is wider than a standard roll of carpet, you will need to purchase more than one length, and to have at least one join. When fitting carpet, you should try to make sure that you have as few seams as possible, and that they are located in an area of the room which has a low footfall – under beds or sofas is ideal, rather than in the main walkway.

Pattern matching and pile direction

Depending on the carpet you choose, seams can be more or less difficult to hide. If your preferred style of floorcovering has a pattern, you’ll need to line up joins so that the pattern matches, which may mean you need to purchase a little more carpet to do this accurately. Every carpet has what is called a ‘nap’. This is the way the carpet pile lies when stroked in one direction. When seaming two pieces of carpet together the nap must be laid in the same direction, or the join will become very obvious.

Measuring for stairs

If you’re recarpeting your stairs, measuring your staircase to find the size of carpet you need to buy can be a little trickier. You need to know the size of the rise (the top of the stair where you place your feet), the fall (the vertical part, or the height of each step) and the width of your staircase. Count the total number of rises and falls to calculate the length of the carpet, remembering to add an allowance for waste and joins. Take into account any stairs that are a different size.

If you have a staircase which is curved, or an otherwise non-standard staircase, you may need to add extra to your measurements. It’s recommended that you get help from a professional carpet fitter if you’re unsure about the best way to measure – mistakes can be very costly!