At Howarth, most of our internal doors fall within a range of conventional sizes, so it's crucial to select the right size for your door. Measuring up for a new internal door is an important step in ensuring a correct fit, so we've put up a brief guide to walk you through the process.

LPD Doors

For measuring a door, the 3 things you will need are:

1. A tape measure

2. Pencil

3. A piece of paper

Helpful tip: If you are buying replacement doors, DO NOT measure the existing door. You must always base your measurements on the door frame itself.

Step 1: Measuring the height

The first thing to do when measuring an internal door is to take a measurement of the inside of each vertical side of the door frame. It is important to measure both sides of the frame since each side may not be symmetrical. Ultimately, the longest length will determine the door's height.

In the UK, the most common door height is 6'6/1981mm, but some may also be 2040mm high.

An infographic of a door being measured by the height of it with instructions attached within the copy.

Step 2: Measuring the width

After that, start measuring at the top corner and work your way across. Repeat this across the middle and at the bottom.Use the widest measurement to ascertain the width of your new door.

An infographic of a door being measured by the width of it with instructions attached within the copy.

Step 3: Measuring the thickness

Lastly, to determine the thickness that your frame will allow, measure the frame rebate where the door will sit after it is closed.
Most doors have a standard thickness of 35mm, however particular areas, such as a kitchen or garage, are likely to have fire doors installed. Fire doors are typically 40mm or 44mm in thickness.

An infographic of a door being measured by the thickness of it with instructions attached within the copy.

Door Measuring Tips

  • Use the dimensions shown above to ensure a perfect fit. Also make sure to double-check all measurements before making a purchase.
  • If you're installing new frames, you might be able to make changes to accommodate common door sizes and prevent the requirement for custom doors.
  • Don't forget to examine how the door opens and take that into consideration. If the floor is uneven or varies on each side of the door, it may impair the ease of opening.
  • Consider the finishing touches you intend to add, such as hinges and handles.

We hope this simple guide has helped you in being able to measure an internal door. If you are interested in looking at our wide range of doors online, you can access our internal doors category here. We also have a huge range of brands to choose from, ranging from LPD Doors , Deanta and JB Kind.

Likewise, the Doors, Floors and Joinery category on our Inspiration & Advice page is full with helpful door guides, ranging from UK Door Sizes, How to fit door architrave, and Understanding Door Construction and Styles.

And if you have any questions on how to measure an internal door, or would just like to know some further information about the products we sell at Howarth, please visit your local friendly Howarth branch, or contact our customer services on the number 01472 907051.

15th Jan 2024 Kacey Gill

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