Point your phone at the night sky, take a photo and upload it. SkyQI's algorithm detects stars, measures brightness gradients and artificial light, then returns your sky's SQM value (mag/arcsec²) and Bortle class — instantly and free. No SQM hardware (≈$150) required.
Get the free SkyQI app: SkyQI - Light Pollution on the App Store (iOS) · SkyQI - Light Pollution Monitor on Google Play (Android)