How the area calculation works
Area = length × width.
Worked example
A rectangle 5 m long and 4 m wide has an area of 20 m².
Guide: using this calculator accurately
For the full explanation, worked examples, measurement tips and FAQs, read the Area Guide →.
How rectangle area works
Area measures the amount of two-dimensional surface inside a shape. For a rectangle, multiply one side by the adjacent side.
Keep your units consistent
If length and width are both in metres, the result is square metres. Do not multiply metres by centimetres without converting first.
Where area calculations are useful
Area is the starting point for flooring, tiles, paintable surfaces, garden beds, mulch, gravel and many other material estimates.
Irregular shapes
For an L-shaped or irregular space, split it into rectangles, calculate each area and add the results. For circles or triangles, use the appropriate geometric formula instead.
Common area mistakes
Remember that area is measured in square units. A 5 m × 4 m rectangle is 20 m², not 20 m.
Frequently asked questions
What is 1 square metre?
It is the area of a square that is 1 metre by 1 metre.
Can I use centimetres?
Yes, but convert the final result to the unit you need. For most home projects, metres and square metres are convenient.
Can area tell me how much material I need?
It provides the surface area, but the material quantity may also depend on depth, product size, coverage and waste.