Most of the windows in our rooms are mostly rectangular.

Why don't we chose any other shape like circle, triangle or trapezium? Does it affects airflow through room? Is the reason is that they look fancy or some specific reason?

  • 3
    $\begingroup$ Most things we do are rectangular because its easy to pack and produce. How many oval tiles have you seen, or triangular phones. $\endgroup$
    – joojaa
    Nov 15, 2019 at 4:37
  • 2
    $\begingroup$ Straight lines are easier to measure and cut $\endgroup$ Nov 15, 2019 at 6:39
  • $\begingroup$ Easier to cut glass in a straight line, which is the main component to a window. $\endgroup$ Nov 15, 2019 at 16:39

2 Answers 2


There are a few reasons on which rectangle comes at optima:

  • Ease of construction and operation (Opening/Closing/Sliding etc) which translates to less expensive.
  • Easy to fit.
  • Less material is wasted when you make the rectangular design.
  • Easy to transport.
  • Strength.
  • One of the purposes of a window is to provide sunlight. A tall window means sunlight for more time as compared to a square window of the same area.
  • Trivial: It is easier to calculate perimeter, area etc of rectangular shape for estimating material, effort etc and thus the cost.
  • A rectangle is visually more pleasing than a square and has more attention span. This is the reason why televisions, books, paintings, photographs etc are mostly or always a rectangle.

More popularity of rectangular shape means mass production and thus even lesser cost on top of the above advantages.

  • $\begingroup$ Porthole windows are easy to open and close... $\endgroup$
    – Solar Mike
    Nov 15, 2019 at 8:54
  • $\begingroup$ You are right @SolarMike. I have written a few points from top of my head. Different shapes may come as winner for specific points. But when you try to find an optimal solution (Something like solving a system of inequations), the rectangle comes out as the winner. $\endgroup$
    – Mohit Jain
    Nov 15, 2019 at 9:11
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    $\begingroup$ Porthole windows need to survive the pressure of sea water etc and sharp corners are a disadvantage. Boat builders had discovered this centuries before aircraft designers learned it the hard way: aerospaceengineeringblog.com/dehavilland-comet-crash $\endgroup$
    – alephzero
    Nov 15, 2019 at 12:04
  • $\begingroup$ @alephzero any sharp change is a disadvantage - especially when things suffer cyclic or shock loads... $\endgroup$
    – Solar Mike
    Nov 15, 2019 at 14:08

processing of long straight pieces of wood is an old industry called millwork.

It is very easy to cut and plane and finish long straight pieces of wood or metal and assemble them into rectangular windows and doors. It is a fortunate thing that evergreen pine and similar species that are used for machining into lumber grow tall and straight, so the millwork done using them tends to warp very little and stay stable over centuries. Most of the saws and finishing machines lend themselves to cut, extrude, long and straight continuous profiles.

This as opposed to round or arched window which is much harder to build and is very likely to warp after losing its moisture content and aging, has been one of the reasons.

Another advantage of using rectangular is because they easily fit into any structure with minimum adjustment. and lest we forget we use a plumb to build our walls perfectly vertical to fight the gravity

Another advantage is the property of the rectangular is to completely tile or cover a surface without leaving any left out areas, be it a house or a highrise or commercial building. It is a very basic way of standardization of windows in construction industry not much unlike standards for the doors, steps, pipe sizes,etc.

Even now that technology can produce wide selection of shaep, the rectangular is the most practical and elegant. Many of turn of century architectural monument established the beauty of using large continuous panels of glass in thin rectangular aluminum frames. frameless glass windows, work seamlessly together because they are rectangular.

And also as has mentioned in comments they are easier to pack and ship.


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