The door opening is the area with-in the inside of the door frame.
To get the dimensions for the door opening
- Get Your Width: Set the tip of your tape measure on the inside of the left frame and measure horizontally to the inside of the right frame.
- Get Your Height: Set the tip of your tape measure on the finished floor and measure vertically up to the inside of the frame header, "to the bottom of frame header".
* Important Information * "Replacement Doors"
If you're keeping your existing door frame and installing a new storefront door then it is important to:
- Single Doors: Subtract 1/4" from the measured door opening width and 3/4" from the height.
- Double Doors: Subtract 1/2" from the measured door opening width and 3/4" from the height.