Flooring Calculator — How Much Flooring Do I Need?

How much flooring do you really need?

Buying flooring is a balance between running out and paying for material you never use. The reliable method is to calculate the net floor area, add a waste allowance and round up to whole boxes. Start with the room length times width, then subtract any area that will not be covered, such as a fireplace hearth, a kitchen island or a built-in cabinet. The calculator then applies your waste percentage and divides by the coverage on one box to give the number of boxes to buy.

Choosing a waste percentage

Waste covers the offcuts at the ends of rows, damaged boards and mistakes. A straight lay in a simple rectangular room typically needs about 5 %, a diagonal layout about 10 %, and herringbone or other patterns about 15 %. Rooms with many corners, doorways or angles need more, and expensive material may justify a slightly higher allowance so you never need a second order from a different batch. Colour and shade can vary between production runs, which is another reason to buy everything at once.

Planks, tiles and cost

If you enter the length and width of a single plank or tile, the calculator also estimates how many pieces you need, which is useful when flooring is sold individually. Add a price per square foot or square metre to see the total, based on the whole boxes you will actually purchase. Switch between imperial and metric units at any time; plank sizes are in inches or millimetres to match how they are sold.

Remember that floors are rarely perfectly square, so measure at several points and use the largest dimensions. Check the manufacturer's coverage per box, because it varies, and leave an expansion gap of about 10 mm around the edges for floating floors. All calculations run in your browser and nothing is uploaded.