While there are no real "standard" sized windows, most home improvement centres will carry a variety of popular sizes. The most common types of windows are single-hung or double-hung, gliders or sliding windows, casement windows and basement styles. Many "specialty" windows are carried in stock. The term "specialty" refers to the irregular shape of the windows and does not denote custom or odd-sized windows.
Single-hung and double-hung windows
Single-hung and double-hung windows are the most common, basic window. They look like two attached windows, mounted vertically. Single hung windows either slide up or open out, with one panel remaining stationary at all times. With double-hung windows, both frames open. These are all-purpose windows, usually used in living areas and bedrooms, but they can be seen in any room of the house. Some standard sizes are 60 cm by 90 or 115 cm (24 by 36 or 46 inches), 70 by 135, 150 or 175 cm (70 by 28 by 54, 66, or 70 inches), and 85 by 105 or 155 cm (34 by 46 or 62 inches).
Gliders or sliding windows
Gliders, or sliding windows, feature two panels side-by-side rather than on top of each other. These are used commonly in bathrooms or porches, but also are usable anywhere in the house. Top sellers are sized at 60 by 57.5 cm (24 by 23 inches), 90 by 90 cm (36 by 36 inches), and 1.2 by 60 or 90 cm (48 by 24 or 36 inches).
Casement windows can be single-framed or double-framed, either horizontally or vertically, but the difference between single- or double-hung and casement windows is that casement windows open out. Because of the way they open, some casement windows don't have screens. Those that do have screens are operated by a hand crank. They usually are used in kitchens, bathrooms, attics and basements. In-stock twin (side by side) casement windows can be found in 52.5 by 112.5 or 132.5 cm (21 by 45 or 53 inch) sizes, while singles can be found at 62.5 by 87.5 cm (25 by 35 inches), or 72.5 by 117.5 or 147.5 cm (29 by 47 or 59 inches).
Basement windows are shorter than normal windows, since they have to fit in the space between the top of the foundation and the ground. Typical basement windows are either sliders, casement windows, vent windows, or they don't open at all. Basement windows usually come in 80 cm (32 inch) widths, with many height options from 37.5 to 60 cm (15 to 24 inches).
Common speciality windows include octagonal windows, in-stock in 55 by 55 cm (22 by 22 inch), 60 by 60 cm (24 by 24 inch), and 67.5 by 67.5 cm (27 by 27 inch) sizes; glass brick windows with in-stock sizes similar to sliders and single- or double-hung; and round-topped windows with in-stock sizes of 125 by 105 or 125 cm (50 by 42 or 50 inches).