How bright are LED lights and how do I know how bright these lights are?

How bright are LED lights and how do I know how bright these lights are?

Because LED lights consume very little power compared to incandescent or even CFL lights but produce comparable brightness, the traditional measure of wattage is inaccurate. The brightness of our lights is measured in lumens. By this measure and from the visible eye, our lights are as bright as or brighter than products using incandescent, halogen or CFL bulbs.