How to Calculate Square Metres (m²)
Learn how to calculate square metres from length and width, convert measurements correctly and estimate simple areas for flooring, tiles, paint, pavers and garden projects.
The basic square metre formula
For a rectangular area, multiply the length in metres by the width in metres.
Area in m² = length in metres × width in metres.
Worked example
A room that is 5 metres long and 4 metres wide has an area of 5 × 4 = 20 m².
How to calculate square metres from centimetres
Convert each measurement to metres before multiplying. For example, 500 cm is 5 m and 400 cm is 4 m, so the area is still 20 m².
How to calculate an irregular area
Split an L-shaped or other irregular space into simple rectangles. Calculate each rectangle separately, then add the results together. This is often easier and less error-prone than trying to use one complicated measurement.
Why square metres matter for material estimates
Many home-improvement products are sold by coverage area. Flooring, tiles, paint, pavers, sod and insulation can all start with an area measurement, although the final quantity also depends on product coverage, thickness, pack size and waste.
Common mistakes
- Multiplying metres by centimetres without converting units.
- Forgetting that area is measured in square units such as m².
- Using one rectangle for a room that actually has multiple sections.
- Assuming area alone tells you the exact amount of material to order.
Use the Area Calculator
For a quick rectangular calculation, enter your measurements in the HomeMathTools Area Calculator.