Let’s be honest: replacing doors is one of the renovation activities that is performed relatively rarely. If it eventually takes place, most of us tend to order the services of a professional fitting team, often offered by the joinery company we purchase from. However, getting professionals to do the job generally entails additional costs. That’s why some customers decide to save money and replace joinery products themselves. In such a case, for everything to go smoothly, you need to know how to measure doors and windows in a proper way. Such knowledge will help you to avoid mistakes that could affect the future use of your house joinery. We have already taught you how to measure windows correctly in THIS article on our blog. Now it’s time to answer the next two BIG QUESTIONS: how to measure doors and how to understand standard door sizes? Have a good read!

Why is it important to accurately measure doors 

In modern door systems, it is not only the product itself that is important, but also the method of its installation. And the latter naturally results from taking accurate measurements for your door. Before starting any construction or renovation work, it is worth familiarising yourself with the consequences of not knowing how to measure door size correctly. In fact, such mistakes may turn out to be quite troublesome in your everyday life. Poorly measured and therefore, incorrectly installed front doors primarily reduce the security of your home. You are exposed to disturbances in acoustics and overall thermal comfort, too. If heat escapes from your home through incorrectly installed external doors, your heating bills will certainly increase. We strongly advise you to read THIS blog article in which we thoroughly explain how the proper choice of your front door may improve the Building Energy Rating of your house. The consequences of wrongly measured doors will also include the accumulation of moisture around the door and even water leaks during heavy rain or snow. Additionally, if you measure doors in the wrong way, they may later rub against the floor and thus, damage panels or floor tiles. It does not look promising, does it?

What are standard front door sizes

There’s no doubt that moving around your house’s interior should be as convenient as possible. And if you ask us, the secret of a comfortable life lies in correctly selected window and door sizes! 

Knowing the standard front door sizes will be very helpful when designing your dream home. In the paragraphs below, our joinery expert and the main fitter in Ireland, Marcin Wojtyczko, will explain how to make sure that the width and height of external doors are adjusted to your needs. 

How to properly measure for a front door – Our Expert has the answer!


The clear opening width and height

As Marcin says, understanding door measurements is essential to ensure that our house doors function properly, provide adequate access and comply with building regulations. The ‘clear opening width and height’ are surely the phrases everyone planning a door installation or replacement should be familiar with. These are the dimensions of the door opening when the door is opened to its full potential. In other words, the opening should be wide and high enough to allow easy passage for all persons and objects (such as wheelchairs or strollers). Typically, front doors must provide a minimum of 900 mm of clear opening width and 2000 mm of clear opening height. 

Non standard door sizes

However, it is always worth considering buying larger doors for your house. The most comfortable front door sizes will include the width of 1000 mm and the height of 2100 mm. They will make it easier to bring in new furniture and allow even the tallest people to move freely. Entrance doors with a height of 2500 or even 3000 mm will look good in large industrial-style buildings. Such impressive door sizes are generally achieved with the use of aluminium or composite profiles characterised by high mechanical strength and durability.

Marcin Wojtyczko would also like to draw your attention to the front doors with side glass panels. They can prove very useful and functional in e.g. large halls with a wide entrance opening. Such glass panels will make your house front doors look stylish and at the same time allow light to enter the interior. A side glass panel is an element consisting of a frame filled with a glazing unit and it can be installed on the sides and/or above the door. Side or top glass panels can enlarge the standard size of a door (1100 x 2100 mm) to approximately 1600 x 3000 mm. If you are interested in top-quality front doors with side glass panels, we strongly advise you to get to know our impressive range of Wikęd composite doors


Obviously, there might always be the need to match the front door to the architectural style of the building. In the case of historic buildings or buildings characterised by original architectural design, it is often necessary to individually order custom-made doors of various widths and heights.

How to measure doors correctly

Installing or replacing external doors in Fenbro customers’ houses is one of the key tasks of Marcin and his team in their everyday work. Therefore, he is perfectly aware that the basis of a successful door purchase is accurate door measurement. Here are some of his expert tips on how to measure door size before you place your order with us! 

Preparing for door measurements 

Start with preparing appropriate equipment – in this case, a 3-metre long measuring tape should be enough. It is important to prepare the door opening well to obtain the correct measurements. You should measure the opening in several places, because there might be a difference in both height and width. If the door opening is uneven, don’t worry – it can be fixed using a special foam or buying an adjustable door frame that can be adapted to unusual heights and widths of door openings.

Measuring for a new door

When you want to measure doors in a new building, you start with checking the width of the door opening inside and outside, in three places (top, middle, bottom). The measurements you eventually take down depend on the door opening direction. If the door opens outwards, you have to add about 10 mm to the outside width. So if you get the width of 900 mm, you need the door that is 910 mm wide – and not more. It is because of door hinges: if the door is too big, the hinges will touch the wall and the door won’t swing properly (at 90°). It is different when the door opens inwards. Then, if during measurements you get the width of e.g. 950 mm, you need the door that is 940-950 mm wide. In the case of inward opening doors, there is enough space inside for the door to open – so the width of your chosen door can be in total accordance with taken measurements.

When measuring the door opening height, you need to know the finished floor level, i.e. concrete plus tile. As a standard, it is 250 mm in total: 230 mm (concrete) + 20 mm (tile, panel) – but these measurements may defer depending on the building project. If the floor is completed, you measure the height from the finished floor level (250 mm) up to the upper door reveal. And then, if you get the height of e.g. 2800 mm, you need the door that is exactly 2800 mm high. If, on the other hand, the floor is not completed, you have to ask the person in charge of the building project what the finished floor level is going to be. Then you measure the door height straight from the given number. 

How to properly measure for a front door – Our Expert has the answer!


The door opening height, similarly as the width, should be measured from both outside and inside of the building. However, remember that the outside measurements are always the most important. It results from the building structural elements – they cannot be changed or modified by our fitting team.  

Measuring for a replacement door

When it comes to the dimensions of the door to be replaced, we measure the width on the outside and then on the inside of the door (in three places: top, middle, bottom). Assuming that both dimensions are the same (e.g. 900 mm), we then add 10 mm to the width and get 910 mm. When the floor level is not planned to be modified in the renovation, we measure the door height from the current level up to the upper door reveal. However, if the floor level is to be increased by a few mm, then we have to subtract this number from the total door height. So if you get the height of e.g. 2800 mm and you know that the floor level is going to be increased by 10 mm, you need to subtract these 10 mm from the final result and order the door that is 2700 mm high.

Generally, it’s more difficult to measure doors for replacement than for a new build. Why? Well, you have to take all factors into account: inside and outside dimensions, floor level inside the house and concrete screed level outside. The amount of subsequent door opening processing will always depend on the correct measurements – the more accurate you are in your measurements, the less additional work is required later.

Measuring the thickness of the wall 

It is the next step in measuring the door opening in the wall. We extend the measuring tape from the edges of the wall, taking into account the planned thickness of the cladding, e.g. tiles. For an adjustable door frame, write down the smallest dimension obtained, for a fixed one – the largest.

Important info!

Remember to measure the height, width, or thickness in several places, as the results may differ slightly. Take into account that differences in measurements may occur even in new construction. If you measure the door frame incorrectly, you will likely buy a door that is too small or too large. In both cases, there will be problems with installing or with tightness. If the ordered door turns out to be too large, you will not have enough space to install it and the only solution may be to enlarge the door opening. Another problem is ordering doors that are too small – here you would have to reduce the door opening. However, both such solutions entail structural considerations (sometimes the walls can’t accommodate a larger door opening without adding structural beams), building permits and obviously, additional costs. Such changes may also reduce the functionality and comfort of using the door. If there is such a risk, definitely consider ordering the doors again, this time in the right size. Keep in mind that the installation warranty covers only the situations where the installation team measures the door as well as instals it. Therefore, correct measurements before ordering are very important.

How to properly measure for a front door – Our Expert has the answer!



The front door is not only an element that adds style to our home. It is also another layer protecting the interior against excessive noise and temperature loss and providing safety and security for both the house and its inhabitants. In order for entrance doors to properly fulfil all of their functions, they must be properly measured and installed. Therefore, if you have already chosen a door system from our offer, ask about the Fenbro door installation services. We constantly recommend the services of our best fitter Marcin Wojtyczko and his installation teams in Ireland. Our fitters get only positive Reviews from our customers who always rate them 5 stars on Facebook and Google.  What is more, if you choose the installation and measurement services by Fenbro, you get a full warranty for the installation as well as after-sales support. When our fitter has measured the door or window openings before your purchase, we take full responsibility for the correctness of the dimensions and you can be sure that the joinery you receive will be correct. Get in touch with our Sales Team to learn all the details!