A new leak shared on Weibo suggests Apple is preparing a notable increase in battery capacity for the iPhone 18 Pro Max, though not every market will get the same capacity. The change appears tied to Apple’s ongoing shift toward eSIM-only designs.
According to the leak, the global version of the iPhone 18 Pro Max — which still includes a physical nano-SIM slot — is expected to carry a 5,235 mAh battery. The US model, likely to remain eSIM-only, could go up slightly to 5,425 mAh.
That split reflects a familiar trade-off. Removing the SIM tray frees up internal space, and Apple seems to be using it.
Battery sizes move up, but not equally
The reported figures translate to a moderate year-over-year increase. The European/global iPhone 18 Pro Max would grow by about 412 mAh over the iPhone 17 Pro Max, an increase of roughly 8.5%. The US variant sees a smaller jump, around 6.6%, from 5,088 mAh to 5,425 mAh.
Context against Samsung and Chinese brands
Samsung’s Galaxy S26 Ultra currently matches the iPhone 17 Pro Max on paper in battery size, yet Apple typically maintains an edge in endurance due to tighter hardware and software integration. The Galaxy S27 Ultra is rumored to move to 5,500 mAh, marking Samsung’s first major battery increase in its Ultra line since 2020.
Chinese manufacturers are already operating on a different scale. Devices like the Xiaomi 17 Pro Max, Oppo Find X9 Pro, and OnePlus 15 have pushed batteries to around 7,500 mAh. In many independent tests, these phones outperform both iPhones and Galaxy devices in sustained usage.
That gap is significant. And growing.
What the increase actually means
A jump to 5,425 mAh on the iPhone 18 Pro Max won’t automatically translate to a proportional gain in battery life. Display efficiency, modem power draw, and background processing all play a role.
The rumored A20 Pro chip, expected to be built on a 2nm process, could be just as important as the battery increase itself. Smaller nodes typically improve power efficiency, extending runtime without requiring massive battery gains.
Even so, Apple’s approach remains incremental. Instead of chasing capacity extremes, it continues to balance internal space, thermals, and efficiency.
That strategy has worked so far. But competition is shifting.
With Chinese brands pushing well past 7,000 mAh and Samsung preparing its own bump, the iPhone 18 Pro Max may find itself in a tighter race than usual — not just on endurance, but on how much battery users expect in a flagship by 2026.
