What to Measure When Replacing Your Old Door

Studies have shown that replacing your old door can save you money on energy costs and give you a better return on your investment when you resell your house. New doors are cleverly designed to keep outside air outside, so your air conditioning unit or heater doesn’t have to work as hard to keep your house at a comfortable temperature. If you live in an extremely hot or cold climate where you find you need to run your air conditioner or heater all the time, having an energy efficient door is even more important. When changing out your old door for a new one, you’ll need to measure each of the following items as best you can to get the best fit and to get the most out of energy efficiency.


  1. Door Size: You will need to measure the height and width of your door as best you can. You can round up inches to figure out exactly what size door you need to order.
  2. Jamb Width: If you look at the interior trim, observe the width of its backside. You’ll need to specify what this measurement is when you order your new door. If the interior trim is not flush with the wall you will need to order jamb extensions.
  3. Rough Opening: In order to get this measurement, you will need to move the interior trim. The rough opening was the measurement of the doorway before the trim was installed.
  4. Exterior casing: this is what encases your walls and the rough opening. It can be brick, stucco, stone, etc.

Sometimes you don’t have to remove the jamb to replace the door. In order to do this, you can start by removing the old door from the jamb by using a screwdriver to unscrew the hinges from the jamb. Leaving the hinges on the door, you then put the new door on top of the old one making sure the edges are even together. Trace the three hinges with a pencil from the old door to the new one. After taking off the hinges you can trace the rest of it on the new door. With a chisel, cut the tracings down at a 1/8-inch depth. Replace the hinges on the new door with the old screws and replace the new door on the jamb. Replace the doorknob and presto, you have a brand new door!