Leaked X-ray images put the base iPhone 18 at 4,430 mAh, more than either iPhone 18 Pro. That's per The Mac Observer, working from a Notebookcheck report on pictures the leaker Littertree66 shared on Baidu Tieba on November 5.
It would be about 20% more than the 3,692 mAh in the iPhone 17. The Pro with a physical SIM tray holds 4,056 mAh and the eSIM-only Pro holds 4,288 mAh, so the base phone would beat them by roughly 9% and 3%.
Apple has split its calendar, so the iPhone 18 and 18e are expected in the first half of 2027, after the Pro models.
The images point to Apple dropping the SIM tray from the base model to make room, and the eSIM-only Pro already carries 232 mAh more than the Pro that keeps one. They also show matching battery compartments, MagSafe coils and similar logic boards in the iPhone 18 and iPhone 18e. Expect the cheaper 18e to get a similar battery.
A bigger cell doesn't guarantee longer life, because endurance also comes down to the chip, the screen and the software. Earlier reports give the base iPhone 18 Apple's 2nm A20 and a 6.3-inch 120Hz OLED screen, and we've already covered the report that it will cost more than the iPhone 17.
Apple has split its calendar, so the iPhone 18 and 18e are expected in the first half of 2027, after the Pro models. Apple hasn't confirmed the battery, and the final figure might differ between regional versions. If battery life is the main reason you'd pay for an iPhone 18 Pro, wait for the first battery tests of the base model before you decide.