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How are rooms' areas calculated ?
How are rooms' areas calculated ?

Check this if you have the feeling numbers don't add up!

Xavier Olland avatar
Written by Xavier Olland
Updated over a week ago

If you look at our floor plans and start calculating room areas to add them up, their total might be different from what is printed. So why is this happening and what is right and what is wrong? The answer is usually simple: not all rooms are rectangular.

The problem of non rectangular rooms

When the floor plan indicates rooms' dimensions, it gives you the largest and widest dimensions. So if you multiply length by width you obtain a larger area than what the room actually is. Look at this example:

The red rectangle has an area of 19'10" x14'10" = 294.19 ft²

But we can see that the rectangle is larger than the room itself. The correct area is defined as shown below in green with the red dots showing the various angles.

The green area is 227 ft²

That's why dimensions can be misleading in non rectangular rooms. So always pay attention to the shape of the room.

How does the calculation actually works

If you don't like math, there's still time to leave!
Our software performs calculations based on the different coordinates of the points that define the area (such as the red dots above).
The type of algorithm used is described on this Wikipedia page.

Excluded areas

Also remember that some rooms can be excluded from the total area with rules depending on the chosen method:

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