Manufacturers measure sofas in inches and sometimes centimetres. These measurements allow you to determine if a sofa will fit in your room, how much seating area exists on the sofa, and the proper coordinating furniture, such as tables or ottomans, you should select to complement the size of the sofa.
Outside measurements are the overall length, depth and height of the sofa's frame and cushions, as measured from behind and to the side of the sofa.
Frame measurements are the length, depth and width of the sofa's frame only. This measurement does not include additional height or depth created by the sofa's cushions.
Inside dimensions of the sofa measure the depth and length of the inner seating area of the sofa with the seat and back cushions placed on the sofa. This dimension tells you the empty space available to sit on.
The arm height of a sofa is the distance from the floor to the tallest point on the arm. This dimension helps you select a side table that is compatible with the arm height.
Seat height is measured from the floor to the top of the seat cushion on a sofa. Depending on the firmness of the cushion, you may sink several inches when sitting on the sofa, so take that into consideration when purchasing a coffee table or ottoman.