{"id":11728,"date":"2023-12-19T09:00:00","date_gmt":"2023-12-19T08:00:00","guid":{"rendered":"https:\/\/www.roomsketcher.com\/?p=11728"},"modified":"2025-02-25T08:03:38","modified_gmt":"2025-02-25T07:03:38","slug":"gross-internal-area-gia","status":"publish","type":"post","link":"https:\/\/www.roomsketcher.com\/blog\/gross-internal-area-gia\/","title":{"rendered":"GIA Explained: The Ultimate Guide to Understanding Property Size"},"content":{"rendered":"

In the world of real estate, where every square foot or square meter counts, it\u2019s important to understand the ins and outs of GIA (Gross Internal Area).\u00a0<\/p>\n\n

Blog<\/a>, <\/span>Floor Plans<\/a><\/div>\n\n
\"Gross<\/figure>\n\n\n\t\t
\n\t\t\t\"Tony\n\t\t\t
\n\t\t\t\tBy<\/span>\n\t\t\t\tTony Gillen<\/a>\n\t\t\t\t
\n\t\t\t\t\tPublished December 19, 2023<\/span>\n\t\t\t\t\tUpdated February 25, 2025<\/span>\n\t\t\t\t<\/div>\n\t\t\t\t\n\t\t\t\t\n\t\t\tImages by Celine Polden<\/span>\n\t\t\t<\/div>\n\t\t<\/div>\n\t\t\n\n\n
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GIA is a standard measurement system used in many countries to measure the internal floor area of a building. This article explains what GIA is, how it differs from other measurement standards, how to calculate GIA, and more.<\/p>\n\n\n\n

What is Gross Internal Area (GIA)?<\/h2>\n\n\n\n

GIA (Gross Internal Area) is the total internal floor area of a building and may also be referred to as Gross Internal Floor Area (GIFA). The Gross Internal Area (GIA) is measured to the inside <\/em>face of the exterior walls and includes all of a building\u2019s floors, both above and below ground. GIA generally includes internal walls or partitions and common building features such as stairs, elevators, hallways, restrooms, storage rooms, machinery rooms, garages, and basements.<\/p>\n\n\n\n

Note that definitions of GIA - including which areas count towards it and which don\u2019t - vary slightly worldwide. Hence, it's best to check with local authorities or a professional appraiser for the most accurate information for your location. Also, when a real estate listing uses GIA, it may refer to the finished <\/em>GIA and have a disclaimer attached to specify the included areas.<\/p>\n\n\n\n

Practical Tips on How to Measure and Calculate GIA<\/h2>\n\n\n\n

Following these steps will enable you to measure and calculate Gross Internal Area for property assessments and real estate transactions.<\/p>\n\n\n\n

Option 1: Use an existing blueprint or floor plan<\/strong><\/h3>\n\n\n\n

If you have an existing blueprint or floor plan for the building, you can import it into floor plan software like RoomSketcher<\/a>, and the software will calculate the GIA for you.<\/p>\n\n\n\n

Option 2: Measure onsite<\/strong><\/h3>\n\n\n\n

You can also measure up the property if you don\u2019t have access to an existing floor plan.<\/p>\n\n\n\n

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  1. Start with a walkaround<\/strong> - Walk around inside the property to get an idea of the shape.<\/li>\n\n\n\n
  2. Sketch the external walls on paper or tablet<\/strong> - Make a sketch of the property shape on paper or create a digital sketch using floor plan software<\/a> on your tablet. Be sure to note key internal wall lengths. At this point, you can import the sketch into floor plan software, and the software can calculate the GIA.
    Or, if you want to measure by hand:<\/li>\n\n\n\n
  3. Find the rectangles<\/strong> - Note whether the building is a simple rectangle or break it down into smaller rectangles (so that you can multiply length x width for each rectangle and add them together).<\/li>\n\n\n\n
  4. Get the measurements<\/strong> - Use a tape measure, roto wheel, or a laser to determine the size of each rectangle inside the property. Measure from the inside of one exterior wall to the opposite exterior wall. If internal walls are in the way, measure to the nearest one, note its width, and then continue to measure.\u00a0 Be sure to document and include internal wall widths in the measurement. Once you\u2019ve measured up one side of a rectangle, go ahead and measure the other direction.\u00a0\u00a0\u00a0<\/li>\n\n\n\n
  5. Do the math<\/strong> - Multiply the length and width of each rectangle to calculate its size. Add together all the rectangular areas on the floor. Repeat for all floors, and sum the result to calculate the building\u2019s GIA.<\/li>\n<\/ol>\n\n\n\n
    \"Measure<\/figure>\n\n\n\n

    Bonus Tip! Use Software to Double-Check Your Calculation<\/h2>\n\n\n\n

    Once you\u2019ve manually calculated the GIA of a building, here\u2019s a way to double-check your work. Pick floor plan software like RoomSketcher, where you get a built-in total area calculator that you can use to double-check your measurement. If everything matches up, then great! If your GIA and the RoomSketcher GIA are way off - you should go back to the property to double-check your measurements.<\/p>\n\n\n\n

    What Areas are Included in a Gross Internal Area Calculation?<\/h2>\n\n\n\n

    GIA describes how much interior <\/em>space is available in a building, both above and below ground. Examples of areas to include in the GIA calculation are:<\/p>\n\n\n\n