According to preliminary tests using a Kill-A-Watt device and OS X system information, the charging profile for the iPhone 6 and the 6 Plus match that of the iPad, allowing them to charge using 2.1A. Unlike earlier iPhone models which would only draw 5W regardless of the charger being used, the new phones are capable of drawing up to 12W, allowing them to charge at a faster rate. Early feedback from owners suggest the larger iPhone 6 Plus can charge fully in approximately two hours from an iPad adapter.
iPhone 5s (l) versus iPhone 6 Plus (r) charging profiles in OS X system report
The iPhone 6 and 6 Plus include the standard square 1A/5W charging block that shipped with previous iPhone models. To obtain these faster charging rates, iPhone 6 and 6 Plus owners may use the 2.1A/12W charger from the iPad or the high-power USB port of a newer model Mac.