The brightness of a 9012-headlight bulb is typically measured in lumens, which is a unit of measurement for the total amount of visible light emitted by a bulb. The brightness of a 9012 bulb can vary depending on the brand and model, but some high-performance options can have a brightness of up to 3,500 lumens. 9012 applications are in projectors so the brightest option for output will be an HID Kit.