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How to Calculate GLA Step by Step

This is the complete walkthrough: from understanding what GLA is, to uploading your floor plan, to reading the final number. Use this as your reference for any GLA calculation.

Step 0: Understand what GLA includes

Gross Living Area counts only above-grade, finished, heated and cooled living space, measured from exterior walls. Before you trace anything, know what goes in and what stays out:

For more detail, see what is GLA and the ANSI Z765 guide.

Step 1: Get your floor plan

You need a to-scale floor plan in JPG, PNG, HEIC, or PDF format. Acceptable sources: CubiCasa, Matterport, iGUIDE, Apex Sketch exports, architect drawings, or a well-taken overhead photo of a printed plan. Hand-sketched non-scale drawings will not give accurate results.

For multi-story homes, get a separate plan for each floor level. Most providers deliver them as separate files or separate pages in a PDF.

Step 2: Upload to the tool

Open MeasureFloorPlan.com and drag your file into the upload area, or click to browse. The file loads in your browser. For multi-page PDFs, the tool loads page 1. Extract other pages as separate single-page PDFs if needed.

Step 3: Trace the exterior perimeter of the living area

Click around the outside of the above-grade living space, placing a vertex at each corner. Work around the full perimeter without stopping. For a standard rectangular home, that is 4 clicks. For an L-shape, 6 clicks. For complex homes, as many as needed.

Do not trace interior walls. Do not include the garage footprint. Close the polygon by double-clicking or clicking the first point again.

For a two-story home, trace the first floor now. You will trace the second floor on its own plan in a moment.

Step 4: Add separate polygons for garage and basement (optional)

If you want to track garage and basement square footage separately, add them as additional polygons. Label each one. They will appear as separate line items in the area summary and will not be added to your GLA total unless you manually sum them.

Step 5: Set scale

Switch to the Scale tool. Click two points along any wall where you know the real-world dimension. Enter that length in feet. The tool recalculates every polygon based on that ratio.

Use the longest dimension you have. Verify scale by checking a second known wall. If both check out, your scale is correct. For detailed guidance, see how to set floor plan scale.

Step 6: Read the result

The GLA total for the traced polygon appears in the sidebar. For a single-story home, that is your GLA. Round to the nearest square foot per ANSI Z765.

For a multi-story home, repeat steps 2-5 for each additional floor plan, then sum the results. Floor 1 GLA + Floor 2 GLA = Total GLA. Do not add garage or basement to that sum.

Step 7: Document your result

Note the source floor plan, the scale reference you used, and the calculated GLA. For formal appraisal or disclosure purposes, note that this is a floor-plan-based calculation and the methodology (exterior perimeter, ANSI Z765 inclusions/exclusions).

Export your measurements as a PDF directly from MeasureFloorPlan.com.