Residential Floor Area Ratio (FAR)

Floor area ratio, or FAR, regulates the amount of gross floor area that can be built on a lot. It is the ratio of gross floor area of building(s) on a lot divided by lot size.

Newton's Zoning Ordinance sets out FAR limits for residential structures and describes what elements of a building are included in gross floor area.

Please click here for a worksheet and accompanying instructions for calculating FAR regulations.

The new FAR regulations tie FAR limits to lot size and zoning district. To see a list of FAR limits by lot size and zone, please click here, or use the FAR calculator below to produce the FAR limit for a particular lot.

For more information, please view the FAQs about FAR, or call the Insopectional Services Department at 617-796-1060. The most common question we've gotten is whether a homeowner can finish an existing basement or attic. The answer is yes, you can finish any space within your existing building envelope without regard to FAR.

For a copy of the FAR regulations , click here.

FAR Calculator

The calculator below estimates FAR limits under the new FAR regulations.
(Make sure to not use commas in the lot size)


* A bonus of .02 is available for construction on lots created before December 7, 1953, provided that new construction complies with setback requirements for post-1953 lots and the new construction does not create or increase nonconformities with respect to lot coverage or open space. The bonus also may not be used in conjunction with Section 30-21 (c) of the Zoning Ordinance, the de minimimis rule.