FilmGauge: Roll Calculator

How much film is actually left on that roll?

FilmGauge answers it in seconds. Measure the roll's outside diameter, choose the film, and you get the remaining length, the area it will cover, and an honest uncertainty band — not a falsely precise number.

THE MATH
A roll seen end-on is a ring. Divide that ring's area by the film's thickness and you have the length wound on the core. FilmGauge runs that calculation against real product specifications, converts freely between imperial and metric, and draws the roll to scale against rulers so every number has something to check it against.

FILM CATALOG
• 350+ bundled presets spanning window film, paint protection film, architectural and decorative film, safety interlayer, and packaging film
• Each preset locks in what never changes — core diameter and film thickness — so you enter only what varies from roll to roll
• Search and filter by producer, brand, or type; shade families collapse into a single row
• Add your own films, and they follow you to your other devices through your personal iCloud account

MEASURE WITH THE CAMERA
Photograph the end of the roll. FilmGauge locates the core and the rim on its own, using your known core diameter as the scale reference, and you can nudge either circle by hand. The photo never leaves your device.

JOB FIT
Enter what you need to cut — piece count, length, overcut, waste — and FilmGauge tells you whether the roll covers the job and how much confidence sits behind that answer.

CALIBRATION
If you know exactly how much came off a roll, calibrate that film's effective thickness against it. Every later estimate for that film gets sharper.

SAVED ROLLS
Recent measurements are kept for you automatically. Pin and name the rolls you care about tracking.

BUILT TO BE TRUSTED
• Works entirely offline
• No account, no sign-in, no ads
• Collects no data whatsoever
• VoiceOver and Dynamic Type throughout
• Light and dark themes

FilmGauge is an independent tool, not affiliated with, endorsed by, or sponsored by any film manufacturer. Preset specifications are drawn from published manufacturer data sheets and provided as nominal starting values. Always verify against your own material before cutting.