How to Measure an External Door | DIY Megastore

How to Measure External Doors

If you’re working on a kitchen renovation, you’ll likely need to decide what to do with old cabinets. They’re crucial components in any kitchen, but like anything in your home, they have a finite lifespan, and will eventually need to be replaced. This can be tricky without the right tools and equipment and can prove problematic if the right steps are not followed.

We’ve put together this guide to help you remove cabinets safely and efficiently. We will cover all the major aspects of kitchen cabinet removal, including the tools you will need, and the steps you will need to take to remove them from your kitchen space. This will enable you to replace the cabinets with a new set or remodel your kitchen as you see fit.

Do I Measure the Door or the Frame?

There are a few different approaches you can take when it comes to measuring an external door. However, it should be noted that some are less effective than others. It is best to avoid measuring your existing door for reference for a number of reasons. One is because your new door needs to fit in completely flush with your frame, which your current door may no longer do after years of wear.

As well as this, if your door is made of wood, it will have changed shape considerably during its lifespan due to minor – yet constant – contractions and expansions. These changes in the shape and size of the door are caused by changes in temperature and humidity levels, and over long periods of time these alterations become permanent.

For accurate results, instead of measuring your door, measure your doorway.

How to Measure a Doorway

Measuring your doorway is relatively simple and straightforward. Before you begin however, you’ll want to know about ‘rough openings.’ These are approximate door sizes that you may spot when shopping for a new door. This size is calculated by adding about 50 – 64mm to the actual size of the door to account for the frame.

If you don’t see this term used to a set of dimensions, assume the frame isn’t being considered. It should be noted that most doors feature a large amount of lipping – the edges of the door that can be planed down considerably to fit a doorway.

Bear in mind that if you’re looking to replace the frame as well as the door, you will need to measure the structural opening – that is, the border around the door frame, usually made of brick.

When measuring a door:

Measure the width of the doorway first by taking three measurements – one at the top, one in the middle and one at the bottom. The largest (after adding those extra millimetres) is your width.
Measure the height of the doorway next. Take three – one on the right, one in the middle, and one on the left. The largest measurement is your door height.
Measure the depth of your frame. This should be relatively straightforward, as there are only three depths commonly used - 35mm, 40mm, and 44mm, though the latter is meant only for fire doors. Measure the depth of your doorframe and work out which of these sizes is closest to your results.

Is There a Standard Door Size?

Now that you have the appropriate tools and have cleared the kitchen ready for work, you can begin to follow our quick and easy step-by-step removal process.

This is a question we are often asked, but the fact of the matter is that there is no ‘normal’ or ‘unique’ door size. Instead, there are a series of general dimensions that are likely to fit the majority of doorways, especially when planed a little to get that flush fit. The most common height for an external door is 1981mm. Meanwhile, widths come in around 838mm for most homes, though they tend to be a little thinner in older builds – around 762mm.

The most common thickness is 44mm, though external doors can be as low as 40mm in thickness. If a door is thinner than this, you may need to check that it isn’t actually an internal door that you are looking at.

Should I Be Measuring in Inches, Feet, Metres or Millimetres?

Another common question, especially on the internet. This is because of the prominence and overlap of American, British, and European blogs and guides that use different units of measurement. Things are particularly confusing in the UK, where we use a mixture of the imperial system (for example, using feet/inches to measure height, and using miles to calculate road distance).

So, which is it for doors? Well, in the UK, suppliers measure their doors in millimetres. This allows for the most accurate measurements for a snug, flush door fit. As such, it’s best to use millimetres when measuring your door. All of our doors are sold with accurate measurements down to the millimetre.

If you find a door measured in inches, you may well be looking at an American site that may not export to the UK. If you’re set on a door measured in inches, there are numerous online calculators that offer reliable measurement conversions, but we’d recommend purchasing a door with millimetre measurements from the get-go.

Conclusion

So, to recap:

Measure your doorway, not your door.
Work out the ‘rough opening of your door.’
Take three measurements (one on each side, one in the middle) for height and width.
It is better to buy a door that is slightly too large than too small, as these can be planed into shape.
You only need to limit your depth options to one of three sizes.

This concludes our look into how to measure your external door for fitting. We hope you now have a clearer idea on how this process is carried out to get the best results. Remember, if you’re looking for guides on other measurements, check out how to measure an internal door. Meanwhile, check out our external door buying guide for more inspiration.

Finally, if you have other questions on internal doors or door DIY in general, do not hesitate to contact our excellent customer services team. With plenty of DIY knowledge and information on all our products, they’ll be happy to point you in the right direction or answer any queries you may have on your next DIY project.

What's Next?

Looking for more inspiration? Take a look at our wide range of product and project guides - covering an array of subjects from garden renovations to painting and decorating, installing stunning lighting set-ups to building out a kitchen or bathroom from scratch and much, much more. Take the leap today and start your DIY journey right here. For direct help and advice, you can also contact our award-winning customer service team.

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