How to Properly Measure for a New Door

Installing a new door might seem a little daunting, particularly if you’ve never done it before. By far the most important thing to think about however, is how to measure for it.

Let’s run through the process of measuring for a new door.

How do You Measure a Frame?

It might be tempting to measure the door you already have in place. After all, if that fits, then surely your new one will, too?

Unfortunately, it’s not quite that simple.

Over its lifespan, an old timber door will warp. It’s far better to measure the frame into which your new door will be installed, instead.

If you’re going to be fitting an entirely new frame, then you will want to double check its size. Most frames will fit standard door sizes, which will help cut costs, but if you’re after something bespoke, then you’ll need to be extra precise.

Before you get started, you’ll need a tape measure.

Step 1: Measuring the height of a door

First, measure the height of the opening in three places: the left, right and middle of the door. These three measurements should be within ten millimetres of one another, or else the entire frame will need to be swapped out. You’ll want to use the shortest of these three lengths; that way you can be sure that the door will open and close properly.

When making these measurements, be sure to account for the height of the carpet, doormats or any other obstacles. That way you’ll be sure that the door can swing freely.

Step 2: Measuring the width of a door

Next, it’s time to measure the door’s width. You’ll do this in much the same way, except horizontally along the bottom, middle, and top of the frame. Use the shortest of the three measurements to determine the maximum size of the door.

Step 3: Measuring the depth of a door

The final step in measuring a door opening is the depth of the door. Internal doors typically come in three different thicknesses, the most common of which is 35mm (although thicker insulating and fire doors might be 40mm or 44mm). Measure at various points along the interior of the frame to be sure of which you need.