How many smartphones are in use worldwide?

How to get close to this number

Start from population and adjust for the two opposing forces. Not everyone has one — children, the very old and the very poor often do not — but many people have two, and businesses issue them. Those cancel out to near parity, which puts the figure close to the world population.

The comparison in the explanation is the one that recalibrates development assumptions: more people have a mobile phone than have a flushing toilet. Mobile networks require towers and handsets, both of which scale cheaply; sanitation requires pipes under every street, which does not. Technologies spread at the speed their infrastructure allows, and radio beats plumbing.

The concentration caveat matters for interpretation. Near-parity in the aggregate does not mean near-universal ownership, because a minority holding multiple devices offsets a large number holding none. Any per-capita technology figure at around one device per person is hiding substantial inequality underneath.