N.Y. ADC. LAW § 27-2074 : NY Code - Section 27-2074: Minimum room sizes

a. In all multiple dwellings erected
  after April eighteenth, nineteen hundred twenty-nine, every living  room
  shall  have  a  minimum  height  of  eight  feet, except as required for
  cellars and basements in section 27-2082 or 27-2083 of article  five  of
  this  subchapter. In a multiple dwelling erected after April eighteenth,
  nineteen hundred twenty-nine pursuant to plans filed and approved  prior
  to  December  ninth,  nineteen  hundred  fifty-five,  and classified and
  recorded in the department, at least one living  room  in  an  apartment
  shall  have  a minimum floor area of one hundred thirty-two square feet;
  if erected, constructed or altered pursuant to plans filed on  or  after
  December  ninth, nineteen hundred fifty-five, one living room shall have
  a minimum floor area of one  hundred  fifty  square  feet.  Every  other
  living  room  of an apartment in a multiple dwelling erected after April
  eighteenth, nineteen hundred twenty-nine  shall  contain  eighty  square
  feet and have a least minimum dimension of eight feet, except:
    (1) A kitchen;
    (2)  A  room  complying with the light and ventilation requirements of
  subdivision a of section 27-2058 of  article  one  of  this  subchapter,
  which  has  an  opening  of  not  less  than  sixty  square feet into an
  immediately adjoining room, may have a minimum  floor  area  of  seventy
  square feet and a least horizontal dimension of seven feet;
    (3)   A   dining  space  complying  with  the  light  and  ventilation
  requirements of subdivision f of section 27-2058 of article one of  this
  subchapter;
    (4)  One-half  the number of bedrooms in an apartment containing three
  or more bedrooms may have a least minimum dimension of seven feet;
    (5) A room in a class B multiple dwelling may have  a  floor  area  of
  sixty square feet and a least minimum dimension of six feet;
    (6) A room in a lodging house, other than an apartment occupied by the
  owner,  janitor,  superintendent  or  caretaker,  shall  comply with the
  provisions of section sixty-six of the multiple dwelling law  and  rules
  and regulations issued pursuant thereto by the department.
    No  living  room,  except  dormitories  in  a  lodging house, shall be
  subdivided or otherwise enclosed unless each such portion complies  with
  the  provisions  of  this  section  and  those for light and ventilation
  required in section 27-2058 of article one of this subchapter.
    b. In a converted dwelling, every living room  shall  have  a  minimum
  height of eight feet, except that a living room located on the top story
  shall  have a minimum height of seven feet in any part located more than
  six feet from the front of such room, and a living room in the  basement
  or cellar shall comply with the requirements of subdivision b of section
  27-2084  of  article  five  of  this  subchapter.  Except as provided in
  subdivision e of this section, a living room in an apartment shall  have
  a  least  minimum  dimension  of six feet, a minimum floor area of sixty
  square feet and a minimum of five hundred and fifty cubic feet  of  air;
  and  a  living  room  in  a  rooming  unit shall have not less than five
  hundred and fifty cubic feet of air, unless it is:
    (1) a kitchen;
    (2) a noncomplying  room  which  has  an  opening  of  not  less  than
  thirty-two and one-half square feet into an immediately adjoining room.
    c.  In  a  new  law  tenement,  every  living  room shall have a least
  horizontal dimension of seven feet, except that  if  a  living  room  is
  either  located  in a dwelling erected prior to nineteen hundred twelve,
  or is a kitchen or a sleeping room for a maid in  a  fireproof  tenement
  where  a  passenger  elevator  is operated, a least minimum dimension of
  only six feet is required. Except as  provided  in  subdivision  e,  one
  living room shall have a minimum floor area of one hundred twenty square
  feet,  and  every  other  room  shall contain seventy square feet if the

  minimum height of the room is nine feet, or eighty square feet  if  such
  room has a minimum height of eight feet, unless it is:
    (1) a kitchen;
    (2)   a   dining  space  complying  with  the  light  and  ventilation
  requirements of section 27-2060 of article one  of  this  subchapter.  A
  dining  space  is  not  permitted  in  an apartment with less than three
  rooms. No living room shall be subdivided or otherwise  enclosed  unless
  each such portion complies with the provisions of this section and those
  for  light and ventilation required in section 27-2058 of article one of
  this subchapter for multiple dwellings erected after  April  eighteenth,
  nineteen hundred twenty-nine.
    d.  In  an  old  law  tenement, every living room shall have a minimum
  floor area of sixty square feet, except as provided in subdivision e.
    e. In a multiple dwelling erected prior to April eighteenth,  nineteen
  hundred  twenty-nine  and  altered  pursuant  to plans filed on or after
  December ninth, nineteen hundred fifty-five:
    (1) At least one living room in an apartment and  any  room  used  for
  single  room  occupancy  shall  have a minimum floor area of one hundred
  fifty square feet.
    (2) All other living rooms in an apartment, or in a rooming unit in  a
  converted  dwelling  shall  have  a minimum floor area of seventy square
  feet, except that a room in a lodging house, other than  a  room  in  an
  apartment  occupied by the owner, janitor, superintendent, or caretaker,
  shall comply with the provisions of section sixty-six  of  the  multiple
  dwelling law and regulations issued pursuant thereto by the department.
    f.  As  used  in  subdivisions  a and e of this section, an alteration
  shall mean the subdivision of any previously existing residential units;
  the combination of residential units with  nonresidential  space  within
  the  multiple  dwelling,  any  of which results in new dwelling units or
  rooming units; or the conversion without physical change  to  a  rooming
  unit, whenever permitted under the provisions of section 27-2077 of this
  article.
    g.  Notwithstanding  any  of  the provisions of this article, in every
  multiple dwelling the minimum acceptable floor area of rooms existing on
  December ninth, nineteen hundred fifty-five shall be the present  lawful
  area,  provided,  however,  that  the  rooms have not been altered since
  December ninth, nineteen hundred fifty-five.