> triple the user base and it's still a lot
WhatsApp current has 430M monthly active users[0], compared with FaceBook's 1.2B[1] monthly active users. Tripling their userbase would make them the same size FaceBook is itself.
ED: Corrected as child comments pointed out.
[0]: http://blog.whatsapp.com/index.php/2013/12/400-million-stori... [1]: http://investor.fb.com/releasedetail.cfm?ReleaseID=821954