As of February 1, 2020, WhatsApp will only support iPhones running iOS 9 or later, Android phones running Android 4.0. 3 or later, and “certain phones running KaiOS 2.5. 1+, including JioPhone and JioPhone 2.”

WhatsApp's support page states that phones with older systems could use the popular chat app until that date. This means that the app will no longer work on these older mobile operating systems.

While Apple typically doesn’t release numbers on how many current phones are running which specific versions of iOS, iOS developer David Smith reports that zero percent of his app users are still running iOS 8. Adoption rates for new iOS versions tend to be quite high; Digital Trends reports that 88 percent of iOS users have updated to iOS 12 a year after release.

Google does share specific numbers on its distribution dashboard, however. Only 0.3 percent of Android devices are currently running Android Gingerbread (2.3. 3 – 2.3. 7). That may not seem like much, but it amounts to about 75 million people worldwide running the older operating system.