Measuring for a prehung door is a crucial step in ensuring a proper fit during installation. A prehung door is a door that comes with its frame and hinges already attached, making it easier to install than a slab door. To measure for a prehung door, you will need a tape measure, a pencil, and a level.
First, determine the rough opening size of the doorway. This is the opening in the wall where the door will be installed. Measure the width and height of the rough opening, and add 2 inches to each measurement. This will give you the overall size of the prehung door you need to purchase.