Apple introduced the iPhone 7 today. It’s 40 percent faster than last year’s A9, and twice as fast as the A8. It’s 240 times faster than the first iPhone. More interestingly, it’s a four-core CPU with two high-performance CPU cores and two “high efficiency” cores that run at one fifth the power to save battery life.
There’s a configuration switch that will route tasks to the powerful cores or the power-efficiency cores. Overall, the iPhone 7 chip uses two-thirds of the power of the previous generation. So the iPhone 7 battery won’t be significantly bigger, but the phone will consume significantly less battery.
Overall, you should get at least two extra hours of battery life for an average day for the iPhone 7 compared to the iPhone 6s. The iPhone 7 Plus should get an extra hour of battery life compared to the iPhone 6s Plus.