32 and 1/2 inches The basic framework should be two and a half inches wider than the door. That leaves 3/4 inch on each side of the door for the finished frame, and 1/2 inch on each side for the shims between the finish frame and the rough frame. A simple way to think about it is that you need three times the width of the door plus some extra room for error.
The height of the frame depends on how high you want the picture to hang. At least 36 inches High is recommended for good visibility. Anything lower may not be noticed if there's anything else in the room with more "crowding" behind it and therefore less attention paid to the painting.
For a wall hanging, the width of the frame should be no narrower than the width of your wall. If you have a narrow wall, you might have to settle for a slightly wider frame to ensure that all of the painting is seen at once.
A framer can help you determine what kind of frame is best for your situation. They will know how much space there is behind the door and where window and electrical boxes are located to provide options for placing hooks or other means for holding the frame together.
Doors come in many sizes and shapes. The most common types are framed with four strips of wood joined by metal hinges or with wooden slats held together with screws.
Size of a Standard Door Frame The usual size of 36 by 80 inches relates to the door panel only, not the frame. The frame extends past the panel and is fitted into the rough aperture. The rough opening should be 3/4 inch wider and 3/8 inch higher than the door frame. The door frame fits into this recess with glass inserted from the inside and screwed down from the outside.
The term "door frame" refers to the structure that supports the door while keeping it closed and locked. It is made of wood or metal. The part that contains the knob or handle is called the stile. The part that extends back toward the room is called the rail. Both parts are sized according to how much weight they have to support. In addition, the distance between the stiles determines how large a hole has to be cut in the wall to allow the door to open and close.
The size of the frame is based on the load it has to support and the distance between its stiles. Usually, the frame is built out of 2x4s for lower-priced doors and frames or 1x6s for more expensive ones. The length of the frame depends on the size of the opening: the smaller the opening, the shorter the frame. For example, a frame for a closet door might be only 30 inches long instead of 40 if it were used as a doorway.