​How to Measure an Exterior Door

​How to Measure an Exterior Door

May 9th 2023

Picking out a style for your new front door can be an exciting task. After all, it has the potential to drastically change your home’s curb appeal. Before you pick out that perfect new door, you’ll need to know the measurements of your current door and entry opening. Accurate measurements are key to making sure your new door is the right size and to ensure you don’t incur any extra costs during installation.

Let’s take a look at how to get these measurements.

Determine What You’re Replacing

The first step is to consider what parts of the exterior door entry are being replaced. Do you want to replace just a single door? What about sidelights or transoms? Will the door jamb and trim need to be replaced as well? This is important to know so you can have all the measurements you need.

Measuring a Single or Double Door

If you are only replacing doors without altering the door frame or door jamb, then you can measure it without uninstalling it first. Using a tape measure, measure the width and height of the door from the interior side. When measuring height, make sure not to include the door sweep.

Next, measure the thickness of the door by simply measuring the edge of the door near the knob or handle.

You will also want to check to make sure your door is plumb and square. You can check of the door is plumb by using a level at the top of your door. To see if the door is square, measure it from top to bottom in an X pattern. If the measurements match, your door is square. If they don’t match, your door might be warped or uneven. In this case, you will want to take more measurements from the sides and take note of the tallest and widest measurements.

Measuring Sidelights & Transoms

Use the same steps for measuring your sidelights and transom windows as you did for your door including checking for plumb and square properties. Record these values separately from the door. You will need to take measurements for the trim as well which may require removing some of the casing.

Measuring the Frame

If you need to replace the entire door system, you will need to measure the door frame. This measurement should not include the interior casing, siding, and any trim pieces on the exterior of the door, so you may need to remove the door and trim to get an accurate measurement. The most common frame depths are 6-9/16" and 4-9/16".

It is recommended to measure the width and height of the frame from the sides, but if your existing door was not plumb and square, you will want to take multiple measurements (at least 3) and go with the tallest and widest.

Now that you have your measurements, you can feel confident in the next step of the door replacement process. Knockety offers a large selection of quality exterior doors that will keep out the elements as well as improve your curb appeal.