I’ve wrote and re-wrote this blog like ten times gang. You guys don’t care about zoning districts and Floor Area Ratios, you just want to know how big your house can be. Well here’s the scoop:
The average lot size on Randlett Park is .19 acres (8,276 sq/ft). The average house size is 2,000 +/- sq/ft.
The max allowable Floor Area Ratio (FAR) for our zoning district (SR3) is .45. This means if you have .19 acres, your home can be 3,724 sq/ft.
Not big enough for you? Since our homes were built before 1954, Newton will allow us to increase the ratio by .02 — bringing total FAR to .47.
Still need more space kemosabe? FAR does not include existing space like unfinished basements or attics.
Link to Newton’s FAR calculator below. Make sure to select Zone SR3.
http://apps.newtonma.gov/floor-area-ratio-calculator
RandlettPark.com 
Does this number also include detached garages?
I don’t believe so. The FAR calculation only takes into consideration the footprint of the house — as measured along the inside walls.