Floor Area Ratio FAR Zoning Calculations

by | Last updated Apr 12, 2022 | NYC Zoning

Floor Area Ratio (FAR) is a mathematical formula that determines how many square feet can be developed on a property in proportion to the lot area. The property area is multiplied by the FAR factor; with the result being the maximum floor area allowed for a building on the lot. Local Zoning Codes will assign a designated FAR based on the zoning district and building use. The size of the building will be directly influenced by the FAR assigned to the specific lot. The larger the FAR, the larger the building can be. Understanding Floor Area Ratio is a basic requirement for real estate development.

Understanding the basics of FAR will allow you to determine how many square feet can be developed on a property, or if there is any room for expansion of a current building on a lot. The FAR calculation can also determine if there are available air rights to sell on the property. This article is based on New York City Zoning but the concepts can apply beyond NYC to any areas that use FAR as a metric for development regulations.


Our Floor area Ratio Youtube Video Explanation 


Zoning Basics Floor Area Ratio NYC

Our Zoning Analysis always starts by figuring out the maximum buildable floor area for your lot. This is the amount of square footage you are allowed to build on the property. The floor area ratio is the deciding factor in finding out the maximum buildable floor area. The floor area ratios are set forth by NYC Planning in the Zoning Resolution (Zoning Code). FAR is the reason why buildings with the same size lot but in different zoning districts can be drastically different in size.


Checking Your Zoning for Floor Area Ratio NYC

Zola, the NYC Zoning and Land Use website is a great resource for finding what zoning district a property is in. After typing in your address, the additional information estimates the zoning district based on the location. All information on this site should be verified by checking Zoning Maps and getting land surveys, but Zola can give you a close reference. Every Zoning District will have a specific Floor Area Ratio and sometimes there are additional Special Zoning District regulations that may modify the Floor Area Ratio.



The local zoning codes will identify what the FAR (Floor Area Ratio) is for your zoning district. Depending on the district, specific property conditions, and proposed building use. In different cases these may be easier or more complicated to figure out. For example a mixed use building may have a different FAR for each use.



For properties in NYC, you can find generic information for each district on the NYC City Planning website. These summarized lists, which come from the Zoning Handbook, are what we call ‘zoning cheat sheets’ at our architecture firm. Be cautious however, as it certainly does not provide all the answers to zoning, which is a couple thousand pages long. Under the Zoning tab there is a ‘Districts & Tools’ section, where you can click on your district and get a glimpse of what the basic zoning regulations are.


Floor Area Ratio Examples


Once you have established your FAR and the area of your lot you can find the maximum buildable area.

How To Calculate FAR


Below you will see an example of a property we investigated for one of our clients. This is in an R7A zoning district in the Bronx. The R stands for Residential Zoning. Zoning districts ending with a letter in NYC are Contextual Zoning Districts. Residential buildings in contextual zones must comply with the Quality Housing Program Zoning regulations.


FAR Calculation Example

Lot Width = 30 Feet

Lot Length = 100 Feet

Lot Area = 30’ x 100’ = 3,000 Square Feet

Zoning District = R7A

R7A FAR = 4.0

FAR x Lot Area = Maximum Buildable Area

4.0 x 3,000 SF = 12,000 SF

This property can be developed with a 12,000 square foot building. This is called the Zoning Floor Area.



Once you have you maximum building area. You can now get an idea of how large of a project you can put onto a lot. You can also subtract the size of the current building on a lot to see how much of an expansion is allowed.


Floor Area Ratio Zoning Calculations

Zoning is complicated and we recommend speaking with a professional . The floor area ratio is just one of the many issues that will affect a new building development or building addition. FAR is a common zoning issue in building construction that any architect should be familiar with.



We hope this post was helpful and we wish you the best of luck with your project. Please feel free to leave comments or questions below. If you are interested in speaking with an architect you can contact Fontan Architecture directly and we will be happy to hear about your upcoming project.


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Jorge Fontan

Jorge Fontan

This post was written by Jorge Fontan AIA a Registered Architect and owner of New York City architecture firm Fontan Architecture. Jorge Fontan has earned 3 degrees in the study of architecture including two degrees from the City University of New York and a Masters Degree in Advanced Architectural Design from Columbia University. Jorge has a background in construction and has been practicing architecture for 20 years where he has designed renovations and new developments of various building types.