When it comes to buying new internal French doors, it’s important you ensure you choose the right size.

Whether you’re replacing an existing set or doors or purchasing for a new frame, you will need to have clear, precise and accurate measurements to ensure that your internal French doors fit.

Understanding internal French door sizes can be confusing so we’ve put together this guide explaining all you need to know about their sizes and how to measure for your new doors.

Standard French doors sizes

While there is no single ‘standard’ size for French doors, most sets of doors will fall within a relatively narrow range of sizes. This is to allow for the slight variation in door frame sizes which exists, particularly across older houses.

The first thing you need to understand when you’re sizing up internal French doors, is what form of measurement to use. The building trade prefers to use millimetres as this allows for the greatest level of precision. For obvious reasons, precision and accuracy are extremely important when it comes to construction.

However, the average home improver might not be familiar with these measurements, and may be overwhelmed by that level of specificity. That’s why some companies (including us) provide key measurements in inches as well as millimetres.

You can always translate these measurements to another form, but to keep things simple, we’ll refer to inches here.

The most standardised measurement for French doors is the thickness. Internal French doors are usually either 35” or 44” thick, depending on the style of door. Thicker doors are better insulators of heat and barriers for sound, but they are also more costly. Here at Doors & More we offer doors in both thicknesses, so it’s entirely up to you which.

The height of internal French doors is also relatively standardised though it does depend on the manufacturer. Most stand at around 6.5ft to fit the common size of modern door frames. However, some retailers (including Doors & More) also stock taller and shorter doors, for homes that need doors which go beyond ‘standard’.

When it comes to the width of internal French doors, things become more complicated. There is no standard size so it is imperative to measure your doors carefully before you look to order.

Our range at Doors & More stretches from 36” right through to 60” wide to fit every common door frame. As well as pairs of doors, you can always install side panels, or single doors to fill out wider door openings (or apertures).

There is no single, hard and fast, one-size-fits-all for any type of door. Internal French doors are no exception, and there is plenty of variation to be had. So before you pick your perfect pair you need to grab your tape measure and get some specific numbers.

How to measure for internal French doors?

As noted above, the only definitive way to ensure that your French doors fit is to measure your home before you order. This is not a hard task to complete, but it is important to be thorough and make sure your measurements are absolutely accurate.

Here’s our step-by-step guide on how to measure, to make sure you get all the numbers you need.

1. Remove your existing doors

This step is not mandatory but it does make your life a lot easier if you don’t a cumbersome door to maneuver around. It will also allow you to get the most accurate width measurements inside the door frame without the hinges obstructing you.

2. Measure the width of the doorway

Take this measurement in three places – once towards the very top, once in the middle and once just above floor level. There may be a slight variation in the width between the top and bottom of the frame – if this is the case then use the shortest measurement.

3. Measure the height of the doorway

Again, you should do this three times, on the left, in the centre and on the right. There is usually a small difference in the frame, particularly in older houses, and you need to make sure your door fits the smallest space.

Note: if there is a big difference in any one set of measurements (width or height) you may need to replace or realign the door frame before installing your doors.

4. Take both measurements again

It is important that these measurements are accurate, so take them twice just to be sure. It is possible to trim wooden doors but the process can be fiddly and difficult to perfect. It is far easier to double check your numbers to start with.

Being meticulous with your measurements might feel time-consuming when your taking them but it is worth it! It is far more hassle to discover your doors don’t fit half-way through hanging them, and far more expensive too if you’re no longer able to return or exchange them.

How do made to measure French doors work?

If the size of your door frame is an unusual size (whether it’s too wide, too narrow, too tall or too short) it is possible to order made to measure French doors.

This will add to the cost of the doors. But the stylish air of perfection that the seamless fit of bespoke doors brings can transform your room.

To order custom French doors, you’ll need the same measurements, though you may be asked to provide more information. If this is an option you want to explore, you can seek more advice about the details you’ll need and the potential costs.