A new leak suggests the iPhone 18 Pro Max could arrive with the largest battery ever fitted to a non-foldable iPhone. The reported numbers also separate the device into two variants, with the eSIM-only model expected to take the lead.
If the leak proves accurate, Apple would be preparing one of its most noticeable battery upgrades in years. The figures also place the upcoming Pro Max in direct comparison with rival flagship phones that have long been associated with large cells.
Two variants, two different battery sizes
The leak says the eSIM-only version of the iPhone 18 Pro Max will use a 5,425 mAh battery. The model with a physical SIM slot is said to carry a 5,235 mAh battery.
That split follows the pattern seen in earlier generations, where the eSIM-only version also received a larger battery than the SIM-equipped model. Apple appears to be using the space freed by the missing SIM tray to increase capacity.
| iPhone 18 Pro Max Variant | Leaked Battery Capacity | Notes |
|---|---|---|
| eSIM-only | 5,425 mAh | Largest leaked battery size for a non-foldable iPhone |
| Physical SIM slot | 5,235 mAh | Still above the 5,000 mAh level |
The same leak also points to a clear jump over the previous generation. The iPhone 17 Pro Max with a physical SIM is said to have a 4,823 mAh battery, while the eSIM-only version is reported at 5,088 mAh.
On that basis, the iPhone 18 Pro Max with a SIM tray would gain 412 mAh, and the eSIM-only model would increase by 337 mAh. For a product line that often changes in smaller steps, those gains would be significant.
Why the comparison with Galaxy Ultra matters
One of the most striking details is how the rumored capacity stacks up against Samsung’s flagship range. The eSIM-only iPhone 18 Pro Max is said to exceed the 5,000 mAh cell reportedly used in the Samsung Galaxy S26 Ultra.
Even the physical-SIM version would stay above 5,000 mAh, which shows Apple may be pushing harder on endurance for the next Pro Max model. Battery capacity alone does not decide real-world performance, but it remains an important signal.
Chip efficiency, software optimization, display behavior, and thermal design all shape how long a phone lasts in daily use. Still, a battery this large would mark a notable shift for an iPhone family that has often relied more on efficiency than raw capacity.
A more aggressive direction for Apple
For years, iPhone battery discussions have centered on optimization rather than pure size. This leak suggests Apple may be pairing its usual efficiency focus with a much larger battery reserve.
That approach would especially matter for Pro Max buyers, who tend to want a large screen and the longest possible battery life. If the figures are correct, the next model could give Apple more room to improve endurance under heavy use.
For now, the numbers remain unconfirmed and should be treated as a leak. Even so, the reported 5,425 mAh and 5,235 mAh capacities have already made the iPhone 18 Pro Max one of the most closely watched future iPhone models.