Is there such a thing as a standard window size?

First of all, the most important information: There is no such thing as a standard or legally regulated window size. Actually, there are almost no limits for building owners and architects with regard to the size of a window. They have the last word and decide whether the window will be round or rectangular, tiny or huge, and whether it will be a single or a double-sash window.
However, there are reasons why you should stick to certain standard sizes when you are building a new house so that no expensive, complicated changes or special constructions are necessary later. It is also practical to consider a minimum size for windows so that sufficient daylight enters the room. But students and tutors at the Fachhochschule für Glas-, Fenster- und Fassadenbau (College for glass, window and façade construction) in Karlsruhe, Germany, have ignored all the standards and built the biggest window in the world. The following article contains more information about standard sizes and records.

The industry determines standard window sizes

If you want to avoid labour and materials costs rocketing sky-high when building a new home, you should pay attention to the standard window sizes specified by the industry. Window fabricators use specific standardised sizes in pre-production. In other words, typical window sizes which house owners can use as guidance in order to avoid reworking, which can be expensive in terms of time and labour, or special constructions.   


When we talk about DIN window sizes in this context, these are not necessarily sizes specified by the Deutsches Institut für Normung (German Institute for Standardisation). Rather, they are window sizes in which the dimensions of DIN 4172 “Modular coordination in building construction” are used as a basis for orientation. With the standard windows presented there and the so-called “basic dimensions”, the height and width of a window always increase in multiples of 12.5 centimetres. However, in each case, you have to subtract 30 millimetres for the installation joints. The resulting DIN dimension windows have the following lengths and widths, for example: 50 x 50 centimetres, 50 x 80 centimetres, 60 x 60 centimetres, 60 x 80 centimetres, 75 x 75 centimetres, 80 x 60 centimetres, 80 x 100 centimetres, 100 x 100 centimetres, 100 x 120 centimetres and 120 x 120 centimetres. 
If, instead, you want to put new windows in an existing building, you should measure the respective openings. In particular, the standard window sizes in older buildings can differ from the new standard sizes.



What is the minimum size for a window?

Even if there are no creative limits for house owners and architects set by standard window sizes, the dimensions are relevant with regard to the incidence of daylight and, consequently, for the atmosphere of the respective room. In other words, there is a minimum size for windows in living areas that you should not undercut for practical reasons alone. 500 millimetres in length and width are suitable for single-sash window and 1000 millimetres in length and width for a double-sash window. Anything below this standard window size will not allow enough light into the room and will also not offer a satisfactory view of the outside.   
Ultimately, light requirements and the purpose of the respective room should determine the size of the window. In other words, the glass surface (also known as light area) that ensures sufficient light during the day is always the right one. However, small and large windows both have their own specific advantages: For instance, small windows offer more protection against heat from outside and also prevent heat loss from inside and are subject to fewer static engineering demands, while large windows provide a better vista, better ventilation options and more daylight.    


What is the world's largest window?

Even for window sizes there is a world record that leaves all standard window sizes well behind. The largest window in the world was built on 19 June 2010 in Germany by master-class trainees and 1st year apprentices at the Fachhochschule für Glas-, Fenster- und Fassadenbau (College for glass, window and façade construction) in Karlsruhe, Germany, in just eight hours. Under the guidance of Professor Layer, the trainees began erecting the 92-square-metre window at 7am and beat the previous record holder by 12 square metres. An impressive feat comprising glass, aluminium capping, pine and Belmadur.