How to calculate area of the house for house insurance purpose?

ask: "How to calculate area of the house for house insurance purpose?"

I know they dont require the basement area.The area given in real estate listing is very different if you calculate on your own with the mathmatical formula= lenth * breath. If you can also tell me how realestate people calculate area of the house. They just give you the range and no body knows what is the exact area and what it covers.

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