Construction
Window Area Calculator
Work out the glass and frame area of windows from width, height and window count.
The Per window result is the area of one window, and the Total result is the combined area of all the windows entered.
Formula
Window area = width multiplied by height. Total area = area per window multiplied by number of windows.
How it works
Measure each window's width and height, then multiply by how many windows share that size. The total area helps with glazing quotes, heat-loss checks and ordering. Measure windows of different sizes separately and add the totals.
Worked example
For example, a window 1.2 m wide and 1.5 m high has an area of 1.2 × 1.5 = 1.80 sq m, so 4 windows of the same size give a total of 1.80 × 4 = 7.20 sq m.
FAQs
Do I measure frame or glass only?
This uses the full opening size, frame included. For glass-only area, measure the visible glass instead.
Why does area matter for energy?
Windows lose more heat than walls, so total window area feeds into heating and glazing decisions.
What about odd shapes?
Split arched or triangular windows into rectangles and triangles, calculate each part, and add them together.
Rough estimate only — consult a licensed professional for structural work before building.
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