A new report by analytics company Localytics revealed that iOS 5 could be on up to 33 per cent of iPhones and iPads.
The new operating system, launched on October 12, has seen enough downloads to appear on a third of all iOS 5 devices, and even taking the new iPhone 4S out of calculations, that's still enough for 31 per cent of devices.
The iPad 2 currently has the highest number of iOS 5, with around 36 per cent installing the software on their tablet. That's closely followed by 35 per cent on iPhone 4, and 33 per cent on the original iPad.
Localytics sourced the figures from analysis of all iOS devices between the launch date and October 17.
The new iPhone 4S became the fastest selling phone ever on release after selling 4 million in just three days.