Plus another 57m on BlackBerry and 12m on Android.
Facebook's recent announcement that it has more than 150 million active mobile users is a considerable underestimate, judging by the social network's published app stats.
Their respective pages on Facebook reveal that its iPhone app has 102.2 million monthly active users, with another 57.5 million using Facebook for BlackBerry, 11.9 million using its Android app, and 2.6 million using its Palm webOS app.
What's more, these figures don't include anyone using Facebook from their Nokia handset - it doesn't have a dedicated application page on Facebook like those listed above.
Nor does it include any users accessing the social network through operator or handset UIs (Vodafone 360, Motoblur etc), or through Facebook's mobile website, which is big in the developing world.
In short, Facebook's active mobile user base is surely already over the 200 million mark, and probably well on the way towards 250 million.
We're scratching our heads over the figures: as recently as June, Apple said it had 100 million iOS devices out in the wild. Meanwhile, in its latest financial results, RIM said it had approximately 46 million BlackBerry subscribers.
Facebook's figures are based on monthly active users though - in theory, all these people have logged in via the apps in the last month.
In any case, Facebook's rocketing mobile presence should give its new Facebook Places geolocation service a fast start.