How to measure a floor and work out how much you need

1. Measure the room

Measure length by width in metres and multiply the two to get the area in square metres. Break L-shaped and irregular rooms into rectangles, work each one out separately and add them together. Measure at the widest point of each section and include doorways and bay recesses that will be floored.

2. Add a wastage allowance

Cuts, pattern matching and the odd damaged board mean you always need more than the bare floor area. A straight, square room with a plank laid parallel to the walls needs the least; herringbone, diagonal layouts and awkward rooms with lots of cuts need the most. Our product calculators offer 0%, 5%, 10% and 15% so you can choose what suits the job, and always round up to whole packs.

3. Convert area into what the product is actually sold in

• Flooring packs: divide your area plus wastage by the coverage per pack shown on the product page, then round up.
• Underlay rolls: divide by the roll coverage and round up to whole rolls.
• Safety flooring and sheet vinyl: sold from the roll by the square metre, so also allow for the roll width when planning seams.
• Adhesive and levelling compound: coverage is quoted per tub or bag, and for compounds it is quoted at a stated depth.

4. Don't forget the rest of the installation

Price up the whole job at the same time: primer and levelling compound, adhesive, underlay and trims. Ordering it together avoids a second delivery mid-installation.