How-Old.net is a new Microsoft website that uses an algorithm to scan a photo of you and tell you how old you are.
It has been very accurate in some cases, and er, not so accurate in others.
Everybody seems to be caught up in the addiction and it is definitely the latest internet trend.
It does sound addictive alright, we'll all be testing every facial expression we have to see if we need to change up our beauty routine a bit.
We tried it out on a few of our favourite celebs, and the results may surprise you (maybe not Kylie though).
Kylie is only 17, we lived our teenage years all wrong…
Oh, North, why so serious? Frowning causes wrinkles, you aren't even two yet…
Poor old Ed, he's only 24!
Sure isn't it amazing what a bit of lippie and a beard can do?