If you are planning to replace an internal door in your home, it is important to know the standard sizes of internal doors in the UK. This will ensure that you choose a door that will fit your doorway and that will be compatible with the other doors in your home.

In this comprehensive guide, we’ll explore the various standard door dimensions in the UK, and the factors to consider when choosing the perfect door for your space.

Now, you might be wondering, “What’s the fuss about door sizes?” Well, hold on tight as we explore the world of standard internal door sizes – trust me, it’s more exciting than it sounds…

Why are standard internal door sizes important?

Before we dive into the nitty-gritty, let’s talk about why standard door sizes are a big deal. Imagine ordering a door that’s too big for your doorway or one that’s too small, leaving weird gaps around the edges. Not a pretty picture, right? Standard door sizes ensure a smooth fit, making installation a breeze and avoiding those forehead-slapping moments.

What is the standard internal door size?

Here comes the technical bit, but don’t worry, we’ll keep it simple and clear. In the UK, standard internal doors come in various sizes, and knowing them is key to making informed decisions.

Door Width (mm) Door Height (mm) Thickness (mm)
457 1981 35
553 1981 35
610 1981 35
686 1981 35
762 1981 35
838 1981 35
864 2032 44
926 2032 44

The below sizes are the British standard for internal doors in the UK. When we say UK, we mean for England and Wales…

OK, let’s break it down:

Single door

The standard internal door sizes in the UK for a single door are as follows:

  • Single door: 2100mm (height) x 762mm (width)

Double door

The standard internal door sizes in the UK for a double door are as follows:

  • Double door: 2100mm (height) x 1524mm (width)
  • Double door with side panels: 2438mm (height) x 1524mm (width)

Other sizes

In addition to the standard sizes, there are also a number of other sizes that are commonly used, such as:

  • Small single door: 1981mm (height) x 762mm (width)
  • Large single door: 2286mm (height) x 762mm (width)
  • Wide single door: 2100mm (height) x 914mm (width)

Fire doors

Fire doors are a type of internal door that is designed to resist the spread of fire for a specified period of time. They’re typically required in commercial and public buildings, as well as in some residential properties e.g. if you rent your property out, you’ll legally be required to install fire doors.

Please note – fire doors in the UK are not the same size as standard internal doors. Fire doors are typically 44mm thick, while standard internal doors are typically 35mm thick. The extra thickness of fire doors is necessary to provide the additional fire resistance.

What about standard door sizes in Scotland?

Fun fact – there’s a difference in internal door sizes between Scotland, England, and Wales.

  • In Scotland, the standard internal door height is 2040mm, while in England and Wales, it is 1981mm.
  • The standard internal door width is also slightly different, with Scotland using a width of 726mm, while England and Wales use a width of 762mm.

Fire doors are also slightly different in size between Scotland, England, and Wales.

  • The standard fire door height is 2032mm in all three countries, but the standard fire door width is 610mm in Scotland and England, and 762mm in Wales.

The reason for these differences is the building regulations in Scotland, England, and Wales are different. The building regulations in Scotland require that internal doors be slightly larger than in England and Wales in order to provide a greater level of fire safety.

For more information about the building regulations around internal doors, the British Woodworking Federation have outlined them here.

So, if you’re replacing an internal door in Scotland, England, or Wales, make sure that you order the correct size door. You can do this by measuring the existing door or by checking with the building regulations in your area. Or by calling Windows & Doors UK.

3 factors to consider when choosing the size of an internal door

1. The size of the opening

One of the most crucial factors to keep in mind when selecting the size of an internal door is, without a doubt, the size of the opening it needs to fit into. It may seem obvious, but you’d be surprised how easy it is to overlook this critical aspect.

Before you rush off to purchase a door, take a moment to measure the width and height of the opening where the door will be installed. Accuracy is key here, so grab that tape measure and make sure to note down the exact dimensions. We’ll detail how to do that in just a minute.

Once you have the measurements, consider a few essential points:

  • Clearance space: Ensure that the door has enough clearance to open and close smoothly without scraping against the floor or adjacent walls. Leave a little wiggle room to avoid any unfortunate door-jamming incidents.
  • Standard sizes: If your opening follows the standard internal door sizes in the UK, you’re in luck! Finding a door that fits will be a breeze. However, if your opening is non-standard, fret not—many manufacturers, such Windows & Doors UK, offer bespoke door sizing options.
  • Opening style: The type of door opening you want can also influence the door size. For instance, bi-fold doors will require more horizontal space to fold into, while a standard hinged door will need sufficient room to swing open.
  • Room proportions: Consider how the door size fits into the overall proportions of the room. A door that is too large or too small may disrupt the visual balance and flow of the space.
  • Architectural constraints: Be mindful of any architectural features or obstacles that might affect the door’s size, such as low ceilings or unusual angles.
  • Future use: Think about how the room’s use might change in the future. For instance, if you’re converting a room into an office that might later become a bedroom, you’ll want a versatile door that suits both scenarios.
  • Wheelchair access: If you need wheelchair access, the minimum clear opening width for a wheelchair-accessible door is 825mm (32.5 inches). This means that the door itself must be at least 825mm wide, and the door frame must also be at least 825mm wide.

2. The type of door

There’s a door for every taste and style, so let’s see what’s behind each one:

  • Panel doors: Panel doors are like the classics—elegant and timeless. They feature raised or flat panels and can effortlessly fit into traditional or modern interiors. A little versatility never hurt anyone!
  • Flush doors: Sleek and contemporary, flush doors are all about that smooth surface. They blend seamlessly with minimalist designs and give your space a neat, uncluttered look.
  • French doors: Ah, the romance of oak French doors! These beauties have glass panes, allowing light to flood through your rooms. Perfect for creating a connection between spaces while still maintaining a sense of privacy.
  • Sliding doors: Slide to the left, slide to the right! Sliding doors are space-savers, making them a fantastic choice for tight spots or those who love a touch of modern flair.
  • Bi-fold doors: Bi-fold doors are like the accordion players of the door world—flexible and fun! They fold in on themselves, creating a wide opening that’s just perfect for connecting indoor and outdoor spaces.
  • Fire doors: If you’re replacing a standard internal door with a fire door, you’ll need to make sure the new door frame is the same size as the old door frame. This will ensure that the door fits properly in the frame and that the hinges and hardware are compatible.

3. The desired amount of light and ventilation

Beyond mere functionality, internal doors also play a vital role in determining the flow of natural light and ventilation within your living spaces. Considering how much light and air you want to allow into a room is an essential factor when selecting the size of an internal door.

Let’s shed some light (pun fully intended) on this aspect:

  • Glass panels or full-glass doors: If you crave bright, well-lit spaces, consider doors with glass panels or full-glass doors. These beauties allow light to pass through, creating a sense of openness and connectivity between rooms. They’re perfect for spaces like the hallway or between the living and dining areas.
  • French doors or sliding doors: Opting for French doors or sliding doors can also enhance natural light intake. With their larger surface area, they offer a more extensive view of the outdoors and let sunlight flood in, creating a cheerful and inviting atmosphere.
  • Rooms with limited windows: For rooms with limited windows, such as interior bathrooms or dressing rooms, choosing a door with glass inserts can help borrow light from adjacent rooms, making the space feel less confined.
  • Ventilation considerations: If proper ventilation is a priority, selecting doors with vents or louvers can facilitate air circulation. Louvered doors are particularly popular for areas like utility rooms, where ventilation is essential.
  • Balancing privacy and light: While maximising light and ventilation is fantastic, don’t forget about privacy concerns, especially for bedrooms and bathrooms. In such cases, consider frosted or tinted glass options, or doors with smaller glass panels.
  • Consider the direction of the door: The direction in which the door swings open can also impact light and air movement. If you want to catch a refreshing cross-breeze, consider installing doors that open towards prevailing winds or towards windows.
  • Room functionality: The purpose of the room should also influence your decision. For example, a study or home office may benefit from ample natural light, while a cosy den or home cinema might call for a bit more seclusion.
  • External obstructions: Take note of any external obstructions that might block light or airflow when the door is open. Positioning your door strategically can overcome these challenges.

What to do if your door frame is not a standard UK door size

Discovering that your door frame doesn’t conform to the standard UK door size can be a bit disheartening, but fear not! There are several solutions to this common predicament. Here’s what you can do if your door frame doesn’t match the standard size:

  • Custom order: Many manufacturers, like Windows & Doors UK, offer custom-made doors to fit non-standard door frames. This option allows you to get a door that perfectly matches the dimensions of your unique opening. Simply provide the exact measurements, and we will craft a door that fits like a glove.
  • Trim the door: If your door frame is just slightly smaller than the standard size, you may be able to trim the door to fit. Keep in mind that this option is best for minimal adjustments, as excessive trimming can compromise the structural integrity of the door.
  • Add fillers or extensions: For door frames that are too large for a standard door, adding fillers or extensions can help bridge the gap. This method involves attaching wooden or metal strips to the door frame to create a snug fit for a standard-sized door.
  • Door frame replacement: If your heart is set on a specific standard-sized door, you can consider replacing the entire door frame to accommodate it. While this is a more extensive undertaking, it can be a great solution if you plan to renovate the space anyway.
  • Pocket door installation: If the width of your door frame is the issue, consider installing a pocket door. Pocket doors slide into the wall, making them an excellent space-saving solution for non-standard door frames.
  • Bi-fold doors: For wider openings, bi-fold doors can be a stylish alternative. These doors are designed to cover larger spaces and can add a unique touch to your interior design.
  • Consult a professional: When dealing with non-standard door frame sizes, it’s essential to seek advice from a professional. A qualified carpenter or door specialist can assess the situation and recommend the best course of action.

How to measure the opening for an internal door

Measuring the opening for an internal door accurately is the first step in finding the perfect door that fits like a charm. It’s a straightforward process, and with a measuring tape and a few minutes of your time, you’ll have the essential dimensions in hand.

Here’s a step-by-step guide on how to do it:

Tools you’ll need:

  • Measuring tape

Step 1: Measure the height

Begin by measuring the height of the door opening. Stand with your measuring tape against the floor, and extend it upward until it reaches the top of the opening. Note down the measurement in either inches or millimeters. Measure from the inside of the top jamb to the inside of the bottom jamb, as this gives you the accurate height of the door opening.

Step 2: Measure the door width

Next, measure the width of the door opening. Position the measuring tape against one side jamb and extend it across the opening to the other side jamb. As with the height, measure from the inside of one side jamb to the inside of the opposite side jamb for precise results. Record the measurement.

Step 3: Measure the depth

This step is optional but helpful if you want to ensure your door is the appropriate thickness. Measure the depth of the door frame or jamb by placing the measuring tape against the interior surface and extending it to the exterior surface. Standard door thickness is around 1 and 3/8 inches (35mm), but it can vary depending on the type and style of the door.

Step 4: Double-check the measurements

To ensure accuracy, double-check all the measurements you’ve taken. It’s not uncommon to make mistakes, and it’s always better to catch them before making a purchase.

Step 5: Consider clearance and swinging direction

While measuring, keep in mind the clearance space required for the door to swing open and close smoothly. Ensure there’s enough room for the door to operate without hitting adjacent walls or furniture. Additionally, consider the direction in which you want the door to swing—left or right—so that it suits your room layout.

Step 6: Record and use the measurements

Once you have all the measurements, record them for reference. Now, armed with the correct dimensions, you can confidently shop for an internal door that perfectly fits your opening.

And that’s it. Our ultimate guide to standard internal door sizes uk. Now all you have to do is choose your int

Tips on choosing the right internal door for your home

  • The style of your home. The style of your home should be the starting point for choosing an internal door. If you have a traditional home, you may want to choose a door with a classic style, such as a paneled door. If you have a modern home, you may want to choose a door with a sleeker style, such as a flush door.
  • The function of the door. Think about how the door will be used. If the door is for a high-traffic area, you will need to choose a door that is durable and can withstand a lot of use. If the door is for a private area, you may want to choose a door that is soundproof or has a frosted glass panel to provide privacy.
  • Your budget. Internal doors can range in price from a few hundred pounds to several thousand pounds. Set a budget before you start shopping so you don’t overspend.
  • Think about the hardware. You will need to choose hinges, handles, and other hardware that matches the style of your door.
  • Consider the finish. You can choose from a variety of finishes, such as solid wood, stained, or painted.
  • Don’t forget the insulation. If you live in a cold climate, you may want to choose an insulated, energy efficient door to help keep your home warm.


Whether you’re looking to install a replacement internal door, or you need brand new internal doors for a new home, let the experts at Windows & Doors UK help you out.

We offer a wide range of high-quality hardwood internal doors, from bespoke doors to common internal door sizes, you can have whatever size of door you want, as all of our timber internal doors are made in our dedicated joinery, right here in the UK. Even better, our professional installers will fit and hang your doors for you.

To find out more, get in touch with our friendly team today.

In This Article…


Laura Wakeham

Laura is an experienced writer with a background in the construction, wood work and hardwood industry - having written for various nationwide publications including Houzz, Construction Weekly and other more local editorial platforms. With over 10 years experience, Laura has detailed knowledge on the ins and outs of hardwood fabrications from orangeries to conservatories, windows and doors.

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