Question 1

Should I include the garage in my floor plan square footage total?

Accepted Answer

No. Under ANSI Z765-2021, garages are always excluded from GLA regardless of whether they are finished or attached. Only enter above-grade, finished, heated and cooled living spaces to get an accurate GLA total.

Question 2

Does this calculator work for irregular room shapes?

Accepted Answer

This calculator uses length × width, which works well for rectangular and roughly rectangular rooms. For L-shaped rooms, split them into two rectangles and add both. For truly irregular floor plans, MeasureFloorPlan's tracing tool lets you click the actual outline of any shape directly on a floor plan image.

Question 3

How accurate is a room-by-room square footage calculation?

Accepted Answer

Room-by-room calculation from interior dimensions is a reasonable estimate but differs from the ANSI Z765 method, which requires exterior wall-to-wall measurement. For loan appraisals, always use the ANSI exterior measurement method. For general planning, room-by-room interior estimates are useful and reliable.

Question 4

Can I use this to calculate GLA for an appraisal?

Accepted Answer

This tool gives you a quick estimate, but appraisals require ANSI Z765-compliant measurement from the exterior. For compliance, you need to measure exterior wall-to-wall from the outside of the home, not from interior room dimensions. Use this calculator for rough estimates; use MeasureFloorPlan with an exterior floor plan for appraisal-grade accuracy.

Floor Plan Square Footage Calculator

How to use this calculator

Related reading

Related tools

Have a floor plan PDF?

Start Measuring Your Floor Plan for Free Today