However, the actual window sizes vary by manufacturer. Each brand typically has its own standard window sizes.
Don’t fret: you can choose standard sizing for the window openings, and then find suitable options from almost any brand.
Standard window sizes for single units fall into a few categories:
- Single-hung, single-wide units often start at 20” by 36”. Common sizes include widths of 24”, 28”, 32”, and 36”; and heights of 36”, 48”, 60”, 72”, and other even numbers.
- Double-hung, single-wide units often start at 40” by 36”. Common widths include 48”, 56”, 64”, and 72”; and heights between 36” and 72”.
- Double width windows have widths of 40”, 48”, 56”, 64”, and 72”.
- Triple width windows, bay windows, sliding windows, and other types can have more variable sizes, with common widths up to 108”.
- Basement windows and other specialty windows are often found with small sizes of 12” by 18”.
Essentially, you can work with the standard window sizes of any manufacturer to find frames that fit within the common opening dimensions.
You may see oddly specific frame sizes because different materials and styles will reduce the actual window size down from the opening dimensions — but these sizes will typically work with one of the standard window sizes listed above.
When planning new construction, the main consideration is to use standard window sizes throughout your house and stick with one manufacturer for most of your windows. That way you will have an easier time finding windows for every space of the house, and more options for treatments.