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Square metres are the standard unit for measuring floor space, walls, land and materials. Whether you're buying flooring, estimating paint, or sizing a room, it starts with one simple calculation: width times length. The tool takes your two measurements in metres and returns the area in square metres instantly.
Enter the width and length, and the area in m² appears at once.
How is it calculated?
The calculation
Area (m²) = width (m) × length (m). A room 4 m wide and 5 m long is 4 × 5 = 20 m².
Keep units consistent
Both measurements must be in metres. If you measured in centimetres, divide by 100 first (350 cm = 3.5 m). Mixing units gives a wrong result.
Practical uses
- Flooring: multiply the room area by the tile or laminate price per m², and add about 10% for waste and cuts.
- Paint: find the wall area (wall length × height), subtract doors and windows, and divide by the paint's coverage per m².
- Land and gardens: for a rectangular plot, width × length; for irregular shapes, split into rectangles and add.
Irregular rooms
For an L-shaped or irregular room, divide it into rectangles, calculate each area, and add them together. For non-rectangular shapes (triangles, circles), an area calculator has the right formulas.
Worked example
A room 4 m wide and 5 m long has an area of 4 × 5 = 20 m². If you're laying laminate priced per square metre, you'd multiply 20 m² by the price and add about 10% for waste — so you'd buy for roughly 22 m². If one measurement was taken in centimetres (say 450 cm long), convert it first: 450 cm = 4.5 m, giving 4 × 4.5 = 18 m². Keeping both measurements in metres is what keeps the result correct.
FAQ
How do I calculate square metres?+
Multiply the width by the length, both in metres: a 4 m × 5 m room is 20 m². Just enter the two measurements in metres.
How do I convert centimetres to metres first?+
Divide by 100: 350 cm = 3.5 m. Both measurements must be in metres before multiplying, or the result will be wrong.
How much flooring do I need for a room?+
Find the room area (width × length), then add about 10% for waste and cuts. For a 20 m² room, buy for roughly 22 m² of flooring.
How do I calculate the area of an irregular room?+
Split it into rectangles, find each area, and add them. For triangular or circular sections, an area calculator has the appropriate formulas.
How do I work out paint quantity from square metres?+
Calculate the wall area (length × height), subtract doors and windows, then divide by the paint's coverage per m² (on the tin). Add a second coat if needed.
How many square feet is a square metre?+
1 square metre ≈ 10.76 square feet. To convert m² to sq ft multiply by 10.76; a 20 m² room is about 215 sq ft.