how to figure countertop square footage

• 
  Silver granite treads
  Silver granite treads
  Flamed and split sides
  Width 12"/14"/20"/24"
  Lenght 48"/60"/72"/84"/96"/108"/120"
  Thickness 2"
  Good price!
  [Categories: Outdoor Products > Steps]
• 
  Silver granite quoins
  Silver granite quoins
  Different Specifications
  Different finishes
  Strong packing
  Good price !
  [Categories: Outdoor Products > Wall Stones]
• 
  Coverings2012 Vanity tops
  Coverings2012 Vanity tops
  22" width vanity tops
  Different marbles and granites available
  Seaworthy packing
  Good price !
  [Categories: Indoor Products > Vanity Tops]
• 
  Granite Columns
  Quality granite columns
  Different designs and finishes
  Strong wooden packing
  Good price !
  [Categories: Indoor Products > Column]
• 
  Golden travertine column cladding
  Golden travertine column cladding
  Finished as per the drawing
  Strong packing
  Good price !
  [Categories: Indoor Products > Column]
• 
  Back granite Column cladding
  Back granite Column cladding
  A lots designs available
  Shiny polished
  Strong packing
  Good price !
  [Categories: Indoor Products > Column]
• 
  Baltic brown granite balustrades
  Baltic brown balustrades
  12x12x75cm
  Brown granite from Finland
  Good price
  Strong packing
  [Categories: Indoor Products > Balustrades]
• 
  Onyx balustrades
  Onyx balustrades
  15x15x75cm
  Yellow colour
  Good price
  strong packing
  [Categories: Indoor Products > Balustrades]

how to figure countertop square footage