Area measurement

ANSI Z765 Finished Area Calculator

Estimate finished square footage while separating above-grade and below-grade areas. This planning tool does not replace a qualified field measurement.

What this calculator estimates

Separate above-grade and below-grade finished areas. It combines the inputs below to produce Above-grade finished area. Every assumption remains editable so the estimate can reflect the property, financing and location being evaluated.

Worked example

Using the displayed sample assumptions, the calculator produces 2,208 sq. ft.. This is an illustration, not a market quote. Change one input at a time to understand what drives the result.

Inputs and assumptions

• Above-grade level 1 length — sample input: 40 ft
• Above-grade level 1 width — sample input: 30 ft
• Above-grade level 2 length — sample input: 36 ft
• Above-grade level 2 width — sample input: 28 ft
• Above-grade exclusions — sample input: 0 sq. ft.
• Finished below-grade area — sample input: 800 sq. ft.
• Unfinished below-grade area — sample input: 200 sq. ft.

How to interpret the result

Confirm the measurement standard required for the assignment. Compare a conservative case with an expected case and keep a record of the assumptions used.

Common mistake to avoid

Do not combine above-grade, below-grade and rentable areas without labels. Local definitions, taxes, lending practices and measurement requirements can materially change the result.

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Reviewed 2026-09-08.