There is a standard rating system, aka ANSI FL1.The problem is a lot of manufacturers, namely Chinese manufacturers, lie about meeting these specs. As for the xt11gt, it is a very impressive light indeed. I dont believe it hits 2000 fl1 lumens, but i think its pretty darn close.Cree states xhp35hi produces about 1500 led lumens at 13 watts. I measured my battery draw at 5.95 amps which is about 22 watts, which I believe is enough to push this led close to 2k Led lumens. Though im unsure how many watts are consumed by the boost driver.As a comparison my malkoff md2 with HOT head drains 1.76 amps, and my doberman pro drains 3.4 amps, which is also very impressive, but the xt11gt produces what looks like twice the output and slightly more throw than the dobermann.