iOS 26 is on most iPhones - just not as many as Apple usually manages.
Apple's App Store metrics for June 2026 show 79% of iPhones running iOS 26, making it the second-lowest adoption rate for any iOS release since 2015. The only release to fare worse was iOS 8, remembered for sluggish performance and a point release so broken Apple pulled it within hours of shipping. Among newer hardware the numbers improve: 86% of iPhones released in the last four years are on iOS 26.
Slow adoption makes developers' lives harder, forcing them to test against more OS versions for longer. It also undercuts Apple's habit of tying headline features to the latest release - a meaningful slice of the installed base simply never shows up.
Apple unveiled iOS 27 at WWDC this month, headlined by an AI-rebuilt Siri that is still in beta. Anyone already dragging their feet on iOS 26 now has a concrete reason to keep waiting.