Apple did not give battery capacities at the keynote, but Europe's energy labels did. According to Tom's Guide, the EU listings put the iPhone 18 Pro at 4,056 mAh and the iPhone 18 Pro Max at 5,391 mAh. Those are the versions with a physical SIM tray, which Europe still sells, so the eSIM-only phones in the US may hold slightly more. Against last year's tray models, the Pro Max battery is about 11% bigger. The Pro's grew by less than 2%.
Apple rates the iPhone 18 Pro for up to 36 hours of video playback, three more than the 17 Pro, and the Pro Max for up to 45 hours, six more. On the smaller phone, almost none of that comes from the cell. The A20 Pro moves to a 2nm process, and Apple says its new C2 modem uses 15% less energy than the C1X, though Apple lists C2 only for the 18 Pro and names no modem for the Pro Max. US capacities will not be known until teardowns after the phones go on sale September 18.