How to calculate how much flooring you need

Calculating how much flooring you need accurately before placing an order is one of the most important steps in any flooring project. Order too little and you risk a batch mismatch when topping up; order too much and you waste money on stock you cannot use. A systematic approach gives you a reliable figure every time.

Measuring the Room

Start by measuring the room accurately. For a simple rectangular room, multiply the length by the width to get the area in square metres. Use a steel tape measure rather than a fabric tape — fabric tapes can stretch slightly and give inaccurate readings over longer distances.

For rooms that are not rectangular, break the space down into rectangular sections and calculate each separately. An L-shaped room, for example, can be divided into two rectangles. Measure each section and add the areas together to get the total. Include any alcoves or recesses — even if they are small, they add up and need to be accounted for in your calculation.

Measure in metres, to two decimal places. A room that measures 4.2 metres by 3.6 metres has an area of 15.12 square metres. Round up to the nearest whole or half square metre when making your final calculation to avoid buying short.

Adding a Wastage Allowance

Flooring is never laid without some degree of cutting waste. Boards at the edges and ends of rows need to be cut to fit, and in rooms with irregular shapes or features such as hearths or bay windows, the cutting can be significant. A wastage allowance should always be added to your measured area.

• Straight lay (parallel to the longest wall) — add 10% to the measured area
• Diagonal lay (45 degrees to the walls) — add 15% to account for the greater number of angled cuts
• Herringbone or chevron pattern — add 15 to 20%, depending on the complexity of the layout
• Rooms with many obstacles or unusual shapes — add up to 20% to be safe
• Stair work — calculate separately, as stair steps are measured and ordered differently from floor area

For example, a 15 square metre room with a straight lay requires 15 plus 10% which equals 16.5 square metres. Round up to 17 square metres when placing the order.

Calculating Pack Quantities

Most flooring is sold in packs that cover a specific area, stated on the packaging or in the product specification. Once you have your adjusted figure (measured area plus wastage), divide it by the pack coverage to find out how many packs you need. Always round up to the next full pack — you cannot buy fractions of a pack.

For example, if your adjusted figure is 17 square metres and each pack covers 2.4 square metres, you need 17 divided by 2.4 which equals 7.08 packs, rounded up to 8 packs. Check the batch or lot number of your order and ensure all packs come from the same batch to guarantee colour consistency.

Planning for Multiple Rooms

If you are laying the same flooring across multiple rooms, calculate each room individually and then add the adjusted figures together before dividing by the pack coverage. Do not combine the measurements from all rooms before adding wastage — each room has its own cutting requirements, and calculating wastage per room gives a more accurate overall total.

Order a few extra packs if the budget allows, particularly for less common or discontinued products. Having spare boards in the loft or garage means that if a board is damaged in the future, you can replace it without searching for an exact batch match. This small additional investment often proves very worthwhile years down the line.