{"id":11902,"date":"2024-03-12T09:00:00","date_gmt":"2024-03-12T08:00:00","guid":{"rendered":"https:\/\/www.roomsketcher.com\/?p=11902"},"modified":"2025-02-25T08:03:17","modified_gmt":"2025-02-25T07:03:17","slug":"net-internal-area-nia","status":"publish","type":"post","link":"https:\/\/www.roomsketcher.com\/blog\/net-internal-area-nia\/","title":{"rendered":"The Ultimate Guide to Measuring Net Internal Area Accurately"},"content":{"rendered":"

In the world of commercial real estate, a building\u2019s Net Internal Area (NIA) is important for communicating the usable space, calculating lease rates, and estimating a property's value. This article discusses the nuances of NIA, walks you through the steps in calculating it, and describes how modern tools like RoomSketcher can streamline this process.<\/p>\n\n

Blog<\/a>, <\/span>Floor Plans<\/a><\/div>\n\n
\"Net<\/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 March 12, 2024<\/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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What is Net Internal Area (NIA)?<\/h2>\n\n\n\n

Net Internal Area (NIA) is a measurement used in commercial real estate to determine the \u201cusable space\u201d within a building. Usable space means the available areas for tenants' exclusive or sole use, such as offices, retail space, labs, and manufacturing. Areas excluded from an NIA calculation include common areas such as shared lobbies, restrooms, or elevators. <\/p>\n\n\n\n

NIA is an essential metric for landlords and tenants, as it provides a standardized way to assess the actual area available for occupation and use within a building.<\/p>\n\n\n\n

Note that definitions of NIA - including which areas count towards it and which don\u2019t - vary worldwide. Hence, it's best to check with local authorities or a professional appraiser for your location's most used measurement standards. Many countries are moving towards International Property Measurement Standards<\/a> (IPMS), developed by more than 80 professionals and non-profit organizations, to document international property measurement standards.<\/p>\n\n\n\n

Practical Tips on How to Measure and Calculate Net Internal Area<\/h2>\n\n\n\n

NIA is basically the total internal area of a building minus the interior walls and common areas. In other words:<\/p>\n\n\n\n

NIA = Gross Internal Area \u2212 (Interior Walls + Common Areas)<\/p>\n\n\n\n

Here are a couple of ways to calculate NIA:<\/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>. With RoomSketcher\u2019s built-in area calculator, you can get your NIA result in seconds - just click to exclude the common areas on the floor plan and then choose the \u201cInternal Zone Area\u201d calculation (which automatically excludes the internal walls for you). <\/p>\n\n\n\n

See Calculate the Total Area of a Floor Plan<\/a> for more information on RoomSketcher\u2019s area calculations.<\/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.  If you know the building\u2019s GIA, you can measure the internal walls and common spaces and subtract them. Or, if you don\u2019t know the building\u2019s GIA, you can add up all the usable space to calculate the NIA. For example:<\/p>\n\n\n\n

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  1. Start with a walkaround<\/strong> - Walk around the property to get an idea of the shape and number of floors.<\/li>\n\n\n\n
  2. Sketch the external walls on paper or tablet<\/strong> - Make a sketch of the property shape or create a digital sketch using floor plan software<\/a> on your tablet.\u00a0<\/li>\n\n\n\n
  3. Note the Usable Space vs the Common Space<\/strong> - Locate the areas or rooms that are usable space and mark these on your sketch. Also, note the common areas intended to be shared among tenants so you do not include them in the calculation.<\/li>\n\n\n\n
  4. Get the measurements<\/strong> - Now, use a tape measure, roto wheel, or a laser to determine the size of any room or area that counts as usable space. It\u2019s helpful to divide the areas into rectangles and measure from the inside of all walls.\u00a0 Once you\u2019ve measured up one side of a rectangle, go ahead and measure the other direction. Remember, don\u2019t include any common areas or shared spaces among tenants.\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 usable areas on the floor. Repeat for all floors, and sum the result to calculate the building\u2019s Net Internal Area (NIA).<\/li>\n<\/ol>\n\n\n\n

    What Does Net Internal Area Include?<\/h2>\n\n\n\n

    NIA describes how much \u201cusable space\u201d a building\u2019s interior contains. Examples of areas to include in an NIA measurement are:<\/p>\n\n\n\n