Floor Area Calculator — Square Metres (m²)
Calculate floor area in square metres (m²) from length and width, with an optional count for repeated identical rooms or spaces. The result also shows square feet for quick conversion.
Enter your measurements
How to calculate floor area in square metres
For a rectangular room or floor, multiply the length in metres by the width in metres. The result is the floor area in square metres (m²). If you have several identical spaces, the calculator multiplies that area by the quantity entered.
Total area = area per space × number of identical spaces
Worked example: 5 m × 4 m room
How to measure an irregular or L-shaped room
Do not measure one large bounding rectangle if part of that rectangle is not actually floor. Split the room into two or more simple rectangles, calculate each rectangle separately, then add the areas together. This gives a much more reliable square-metre figure for flooring, screed, insulation, decorating and general estimating.
For a fuller measuring walkthrough, use the How to Calculate Square Metres guide. If you already know the area and only need to change units, use the Area Converter.
What should you measure to?
Flooring finish
Measure the actual floor area the finish will cover. Alcoves, recesses and fixed obstructions may change the usable area depending on the installation.
Subfloor or screed
Use the dimensions of the area receiving the layer. Keep thickness separate because thickness turns an area calculation into a volume calculation.
Repeated spaces
Only use the quantity field when the rectangles are genuinely identical. Measure different rooms separately and add their areas.
Square metres, linear metres and cubic metres are different
A floor area is measured in square metres (m²). Linear metres measure length only, while cubic metres measure volume. If a product is sold by linear metre, use the Linear Metre Calculator. If you need volume from length, width and depth, use the Cubic Metre Calculator.
Common floor-area measuring mistakes
- Mixing centimetres or millimetres with metres before multiplying.
- Measuring an L-shaped room as one oversized rectangle.
- Using the identical-area quantity field for rooms that are actually different sizes.
- Confusing square metres with linear metres when ordering flooring or trims.
- Adding a material waste allowance to the room measurement itself instead of keeping the measured area and ordering allowance separate.
Using floor area to estimate materials
The measured floor area is usually the starting quantity rather than the final order quantity. Once you have the m² figure, move to the material-specific calculator so pack coverage, board dimensions, tile size or waste allowance can be handled explicitly. Useful next tools include the Laminate Flooring Calculator, Tile Calculator, Floor Screed Calculator and Insulation Board Calculator.
Planning estimate only. Measure the real job and follow the selected product’s coverage, fitting instructions and ordering units before purchasing.
Frequently asked questions
How do I calculate the square metres of a floor?
Measure the floor length and width in metres, then multiply them. A 5 m by 4 m rectangular floor is 20 m².
How do I calculate the area of an L-shaped room?
Split the shape into two or more rectangles, calculate the area of each rectangle, then add the results together.
How many square feet are in one square metre?
One square metre is approximately 10.764 square feet. The calculator shows the square-feet equivalent automatically.
Should I include alcoves when measuring floor area?
Include any area that the material will actually cover. Measure recesses and alcoves separately when that makes the shape easier to calculate accurately.
Should I add flooring waste to the measured floor area?
Keep the measured area as the real geometry first. Add the appropriate waste or cutting allowance later using the relevant material calculator or product guidance.
Can I use this calculator for several rooms?
Yes when the rooms are identical: use the quantity field. If their dimensions differ, calculate each room separately and add the areas.
Related measuring tools
Need wall area instead? Use the Wall Area Calculator. For unit conversions and more site-measurement tools, return to the Measuring & Conversions calculator hub.