Window-to-Wall Ratio Calculator
Compare total window area with gross exterior wall area.
What would you like to do next?
Express glazing as a share of gross wall area
Enter exterior wall length, floor-to-floor wall height and total window area for the same wall scope. The calculator finds gross wall area, caps window area at that total, reports opaque area and window-to-wall percentage, then compares the result with an editable ratio to show the corresponding target area and difference.
Geometry does not predict complete performance
The ratio alone does not assess orientation, climate, glazing properties, frames, shading, daylight, glare, structure, condensation or energy-code requirements. Keep wall and window scope consistent and use an appropriate building model and local requirements for performance decisions.
Frequently asked questions
Which wall height is used?
Enter the floor-to-floor height for the gross wall area being reviewed.
Are doors included as windows?
Only include glazing according to the scope and definition used by the project.
Does a ratio measure energy performance?
No. Glazing properties, orientation, shading, climate and the full assembly also matter.