How to measure windows for window film

Before you bid, walk the windows: the size of each pane, how many are alike, the glass type and the panes to check. A worked example and a free calculator are waiting at the end.

Window film calculator

What to bring

A rigid tape measure
A flashlight to read the glass marks (tempered, low-e)
A sturdy ladder for high panes
Your phone to record and photograph each facade in a MesuPro survey

For high panes, work from a sturdy ladder or a platform, and note the access in the survey. Do not scrape old film off fragile glass without checking it first.

Step by step

Measure the visible glass
The width and height of the glass you see, frame edge to frame edge, not the whole window. Record them in inches or millimeters.
Group the identical panes
One row per size, with the number of identical panes: an office facade often has only a few sizes.
Record the glass type
Single or double, tempered or annealed, tinted, low-e. No tempered mark: presume annealed glass.
Spot the panes to check
A double pane over 40 sq ft, thick or tinted glass, exterior shading: the film maker's film-to-glass review comes before installing.
Estimate the film and the rolls
The film area is the visible glass. The rolls depend on their width and your cut: each piece is cut a little larger than the glass, then trimmed in place.

The calculation

Pane area = width x height; film area = area x identical panes, added up over every row. A pane over 40 sq ft (3.7 m²) is counted to check: the film maker's film-to-glass review comes before installing. Rolls = film area x (1 + waste) / (roll width x roll length), rounded up to the roll: an estimate, the real cut depends on how the pieces are laid out. No roll width or waste comes filled in: they are yours.

Worked example

On the fictitious office building of the demo "Window film - Office building, Richmond VA", 42 panes of 54 x 72 in on the south and west facades, 4 lobby panes of 96 x 120 in and 12 panes of 36 x 72 in in the server and mechanical rooms make 58 panes and 1,670 sq ft of film. The 4 lobby panes are over 40 sq ft: check them first. With a 60 in by 100 ft roll and 10% waste, that is about 4 rolls before the cutting plan.

Try it with your numbers