Apple’s upcoming iPhone 18 Pro Max could feature the largest battery ever fitted to a non-folding iPhone, according to a new leak that claims to reveal the handset’s battery capacities ahead of its expected September launch.
The leak suggests Apple will continue offering different battery capacities depending on the model’s SIM configuration, as it reportedly did with the previous generation.
According to the report, the eSIM-only version of the iPhone 18 Pro Max will pack a 5,425mAh battery, while the variant equipped with a physical SIM slot will feature a slightly smaller 5,235mAh battery.
If accurate, the larger battery would make the iPhone 18 Pro Max Apple’s biggest battery upgrade yet and would even exceed the 5,000mAh battery found in Samsung’s flagship Galaxy S26 Ultra.
The reported figures also represent a notable increase over the iPhone 17 Pro Max. The physical SIM model of Apple’s current flagship is equipped with a 4,823mAh battery, while the eSIM-only version carries a 5,088mAh cell.
That would translate into a 412mAh increase for the physical SIM variant and a 337mAh improvement for the eSIM-only model.
Apple has traditionally focused on software optimisation and chip efficiency rather than increasing battery capacity. However, larger batteries could help offset the additional power demands expected from next-generation artificial intelligence features, brighter displays and more powerful processors.
The iPhone 18 Pro Max is widely expected to launch alongside the rest of the iPhone 18 lineup in September, although Apple has not officially confirmed any specifications.
As with all pre-release leaks, the reported battery capacities remain unverified, and Apple could make changes before the devices are officially announced.