The new iPhone 6 and 6 Plus come out today. Both are a bit bigger than previous versions of the phone, and that means using them is a little different. Over on Quartz, designer Scott Hurff shows how reachable the new phones are.
Obviously everyone's hands are different, but Hurff created a map of the "Thumb Zone" using research from Steve Hooper. The result is that you'll have to stretch out your thumb quite a bit to hit everything on the iPhone 6 and the iPhone 6 Plus is basically impossible to use one-handed. Apple solves this problem with Reachability, a new one-handed mode for the new models, but it's still good to know what you're getting into. The same goes for any larger phone. Hurff has a ton of data and insights over on Quartz if you want to see more.
How to design for thumbs in the era of huge screens | Quartz