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Square metre calculator

Most materials are sold by the square metre. Measure in metres, pick the shape, and this gives you the area to take to the shop.

m

2400 mm is 2.4 m.

m
m
m

Measured square off the base, not along the sloping side.

m

Straight across the middle.

Allowances and fine-tuning
%

Covers offcuts, breakages and mistakes. Set it to 0 for the bare figure.

An estimate to plan with. Check sizes and quantities with your supplier before you order.

How it is worked out

Rectangle: length × width. Triangle: base × height ÷ 2. Circle: 3.1416 × diameter × diameter ÷ 4.

Everything is in metres. To turn millimetres into metres, divide by 1,000, so 3,650 mm is 3.65 m.

For an L-shaped room, split it into two rectangles, work each one out and add the two answers.

Worked example

The numbers this page opens with: Shape: rectangle, length 4 m, width 3 m, extra for waste 0 %.

The answer: area 12.00 m²; distance around the edge 14.00 m.

Questions

How do I measure a room that is not a simple shape?

Break it into rectangles and triangles, work out each piece and add them up. Bay windows and alcoves are just more small rectangles.

Is a square metre the same as a metre squared?

A square metre (m²) is an area. "Three metres squared" is sometimes used to mean a 3 m by 3 m square, which is 9 m². When you order, give the area in square metres.

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