Door & Window
Door Size Calculator
Rough opening and structural opening sizes for a door, with the frame and clearances.
opening = leaf + fitting gaps + frame thi…
Also called door rough opening · door frame size
Home & Construction · 7 calculators
Door & Window Calculators
Door rough openings, window and glass area, window-to-wall ratio, curtain and blind sizes, door and window paint.
Door & Window
Window Area Calculator
Glazed area, frame area and total window area for one or several windows.
glazed area = (width − frames) × (height …
Also called glass area calculator · window square meters
Door & Window
Window to Wall Ratio Calculator
Window-to-wall ratio for daylight and energy compliance, with the daylight factor estimate.
WWR = window area ÷ gross wall area × 100
Also called wwr calculator · glazing ratio
Door & Window
Curtain Size Calculator
Curtain width and drop from your window and pole, including the fullness ratio and fabric needed.
fabric = ceil(pole width × fullness ÷ rol…
Also called curtain fabric calculator · curtain width calculator
Door & Window
Blind Size Calculator
Blind width and drop for inside or outside recess fitting, with the overlap allowances.
inside fit = recess − clearance
Also called roller blind size · blind measurement calculator
Door & Window
Door Paint Calculator
Paint needed for doors and frames, counting both faces, edges and the architrave.
area = (door faces + frame) × doors, litr…
Also called paint for doors · door and frame paint
Door & Window
Window Paint Calculator
Paint for window frames and sills, with an allowance for the extra area glazing bars add.
frame area = perimeter × frame width, dou…
Also called paint for windows · window frame paint
Key door & window formulas
| Door Size | opening = leaf + fitting gaps + frame thickness both sides |
|---|---|
| Window Area | glazed area = (width − frames) × (height − frames) |
| Window to Wall Ratio | WWR = window area ÷ gross wall area × 100 |
| Curtain Size | fabric = ceil(pole width × fullness ÷ roll width) × cut drop |
| Blind Size | inside fit = recess − clearance · outside fit = recess + overlap |
| Door Paint | area = (door faces + frame) × doors, litres = area × coats ÷ coverage |
| Window Paint | frame area = perimeter × frame width, doubled for both sides |