PWM Flicker Test: FlickerGauge

See the flicker your eyes can feel but cannot see — on a phone screen, a monitor, a lamp.

Point the camera at the screen or the light and hold still for two seconds. FlickerGauge reads the stripes the camera's rolling shutter paints and turns them into numbers: how fast the light flickers, how deep the dips are, and where that lands against IEEE 1789, the recommended practice for flicker in LED lighting. Frequency is free, forever.

HOW IT WORKS
1. Aim. A lamp: at the wall or table it lights. A screen: show a blank white page and turn its brightness down — most screens only flicker when dimmed.
2. Hold steady. The reading settles in about two seconds, and every number carries its error bar.
3. Read the verdict. Safe, caution or fail — read off the whole error bar, never rounded. When it is borderline, the app says so.

WHAT YOU GET
• The flicker frequency of any screen or lamp, with its error bar — free, without limit.
• Modulation depth with error bars, and the IEEE 1789 verdict where depth decides it.
• A community database of phones, monitors, laptops and lights, measured by brightness level — check before you buy, offline.
• Your own measurements kept on the phone, and a card to share for each.
• A one-minute calibration against any mains lamp, so the numbers are exact for your camera.

THE METHOD IS PUBLIC
The Guide inside the app explains the whole method, its limits and its error bars. This is not a laboratory photometer, and the app says so.

WHAT YOU NEED
• An Android phone whose camera allows manual exposure. If yours does not, the app says so plainly instead of showing a number it cannot stand behind — the database still works.
• A dim room helps: bright surroundings wash the stripes out.

PRIVACY
The camera is used to measure, not to photograph: frames are analysed in memory and discarded. Nothing leaves your phone unless you choose to add a measurement to the database — anonymously, and the app shows you exactly what is sent first. No account, no sign-up, no advertising. Crash reports can be switched off in Settings.

WHAT IT COSTS
Measuring frequency is free forever, and so is every verdict that frequency alone decides. Depth, the verdicts in between, the database search and the share cards are a single one-time purchase — there is no subscription. Adding your measurement to the database is free for everyone. Restore takes one tap on a new device.

Languages: English, Russian, Spanish, Uzbek.

FlickerGauge measures how a light or a screen flickers. Flicker is linked to eye strain in sensitive people; the app makes no medical claim and diagnoses nothing. Depth is an estimate with stated error bars, not a laboratory measurement.