Marco Arment, developer of Instapaper, has provided some intriguing usage stats for his bestselling app. While the numbers aren't representative of the entire iOS ecosystem, the fact that Instapaper is a popular paid app (almost always in the top 5 paid apps in the News category on the App Store) makes these stats worth looking at for developers looking to efficiently design and market their apps.
The majority of Instapaper users (56 percent) are using the app on an iPad, versus 39 percent on iPhone and a tiny six percent on the iPod touch. In only four months of availability the iPad 2 accounts for over 27 percent of devices using Instapaper, with usage numbers already nearly identical to those seen from the original iPad. As a universal app and a news reader, it's not particularly surprising that iPad adoption is so high among Instapaper users, but the huge jump in iPad 2 numbers in such a short time is rather startling. Based on the numbers he's seeing, Arment estimates that approximately 40 million iPads have been sold since its introduction.
As for OS compatibility, 99 percent of Instapaper users are using iPhone OS 3.2 or above, and 98.4 percent are on iOS 4 or later. After taking into account the high adoption of iOS 4.2 and above (96 percent of users) and the tiny number of users running Instapaper on devices that can't be upgraded to iOS 4 (0.4 percent of users still running an original iPhone or iPod touch), Arment has decided to make iOS 4.2 the minimum supported OS for the next release of Instapaper.
According to Arment, dropping support for versions of iOS earlier than 4.2 has allowed him to streamline Instapaper's code in several ways. 5.4 percent of his users are running Instapaper on devices that are capable of running iOS 4.2, but for whatever reason those users have yet to update. If you're one of those users, now's the time to update your OS... and if you're still running a first-gen iPhone or iPod touch and want to keep Instapaper current, it's time to upgrade your hardware.
Other iOS developers can learn a lot from Instapaper's usage stats. While the stats for your app are probably going to be a bit different, it seems that as time goes by the number of users actively using older iPhones and older versions of iOS steadily declines to the point that it's no longer efficient to support them. Arment estimates that the number of Instapaper users still using an iPhone 3G will diminish significantly after the iPhone 5 hits the market, which means many types of apps (games in particular) may benefit from dropping support for that model iPhone sometime in the next few months.
If you're in the same position as Arment -- looking for ways to improve your app's codebase and considering dropping support for earlier hardware and iOS versions -- it's worth comparing your usage stats to his and seeing if, like him, you'll be better off in the long run by bumping up your app's base requirements.