Calculate construction area

This construction area calculator works out the area of any rectangular space from its length and width. Enter the dimensions in metres, feet, or yards and it returns the area in square metres, square feet, and square yards, plus the perimeter. It is ideal for estimating flooring, tiling, paint, decking, turf, slabs, and other materials sold by area.

How to measure area

For a rectangle, area = length × width. For an L-shaped or irregular space, split it into rectangles, calculate each part, and add them together. Always measure at the widest points and add about 10% extra when ordering materials to allow for cuts, waste, and breakages.

Estimating materials by area

Once you know the area, you can estimate quantities: paint coverage is usually given in m² per litre, tiles and turf are sold per m², and decking per linear or square metre. For depth-based materials like concrete and gravel, use our concrete calculator and gravel calculator, which factor in thickness.

Frequently asked questions

How do I calculate square metres?

Multiply the length by the width, both measured in metres. A room 5 m long and 4 m wide is 20 m².