When you buying a new door, you have the option of buying it pre-hung on the frame or just the door itself, called a slab. So, you'll need to learn how to measure a door to ensure you're buying the right size. Here are a few pointers to help:
- If you're buying just the door itself, measure just the existing door (height, width, and thickness).
- When buying a pre-hung door, open your existing door and measure from one side of the frame to the other. Measure from the top of the frame to the floor. Then subtract 3/4 of an inch for floor clearance. You'll also need to measure the jamb thickness so your new door fits snugly inside your walls.
- Consider a custom door if standard door sizes don't meet your needs.
How to Measure
Use a tape measure to determine the height in three different places: the center of the door, the left side, and the right side. Write down the shortest measurement of the three.
Repeat the same process for the door's width by measuring the top, middle, and bottom, recording the shortest of the three. Measure both the inside and outside of the door.
Finally, measure the depth of the door by opening it and measuring its thickness.