Density

Density Factor / Dwelling Unit Factor

(Last Updated On: December 6, 2018)

Density Factor is a zoning term for the maximum allowable number of residential units one can develop on a property. The allowable residential square footage of the building is divided by the density factor to determine the allowable number of units. These factors vary in different zoning districts. Density factor is also known as Dwelling Unit Factor.

 

Zoning Basics : Density Factor

Density Factor Definition

The following is based on The New York City Zoning Resolution.

Density Factor is a formula for determining how many dwelling units can be placed on a lot. The density factor or dwelling unit factor is based off the zoning district for that location. The zones are divided into lower and higher densities. It is NYC`s way of regulating density throughout the city.

 

Finding Your Density Factor

In order to calculate your density factor you need to calculate your Maximum Buildable Area, which you can find information to do so in our Floor Area Ratio post. Once you have that you will have found your zoning district and below you will find your Factor For Dwelling Unit based on that.

 

DU Factor NYC Zoning

District Factor for Dwelling UnitsSpecial Notes
R1-14,750
R1-2 2,850
R2
R2A
1,900
R2X2,900
R3-1
R3-2
625R3-2 for single and two family detached and semi-detached residences only
R3A 710
R3-2
R4
R4-1
R4B
870
R3X1,000
R4A1,280
R4 Infill
R5 Infill
R5B
900R4 Ifill & R5 infill In Predominantly Built Up Area only.
R5
R5D
760
R5A1,560
R5B1,350for lots with less than 40 feet street frontage and existing on the date of establishing the R5B districts on the zoning map.
R6
R7
R8
R9
R10
680This goes for all R6 - R10 Districts including subdistricts and contextual zoning.

 

DENISTY FACTOR CALCULATION

Maximum Buildable Area for Residential X Factor for Dwelling Units = Dwelling Units Allowed

Example

Maximum Buildable Area = 9,000 SF

Zoning District = R6

Factor for Dwelling Units = 680

Maximum Buildable Area /Factor for Dwelling Units  = Number of Dwelling Units Allowed

9,000 SF / 680 = 13.23

13 Units  would be allowed

 

DENSITY FACTOR KEY POINTS TO CONSIDER

  • You can only round up Density Factor if you have a value with .75
  • Small zoning lots are restricted to 1 and 2 families even if the density factor allows for more then 2.

 

DWELLING UNIT COUNT

Your maximum unit count will tell you how many apartments you can put on a lot. You can also use it to see if you can expand and existing building to add more apartments to it

 


THANK YOU FOR READING OUR POST ON DENSITY FACTOR AND DWELLING UNIT CALCULATIONS.

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. Learn more about our New York Architecture Firm.

 

New York Architects, Jorge Fontan

Author Jorge Fontan AIA

This post was written by Jorge Fontan, a Registered Architect and owner of Fontan Architecture.

2 Comments

  • Denny Wu

    June 11, 2018 10:22 pm
    Reply

    I have a 25×100 lot with a semi detached single family house already on an R3-1 zoning. does that mean I can convert it to a 2 family since .5×2500= 1250 with a density factor of 2? a previous architect told me that it couldn’t be done and said that there’s not enough space

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