iPhone 18 Pro Max battery leak: up to 5,425 mAh, but Chinese rivals still pack 7,500
The iPhone 18 Pro Max is shaping up to carry the largest battery Apple has ever put in an iPhone, according to figures published by GSMArena and 9to5Mac. The US eSIM-only variant is reported at 5,425 mAh, while the physical-SIM version sold in the UK and Europe reaches 5,235 mAh. Both figures mark the first time a Pro Max has clearly surpassed the Samsung Galaxy S26 Ultra's 5,000 mAh on raw capacity.
Why two different numbers
The gap comes down to hardware, not software. A nano-SIM slot takes up physical space inside the chassis; drop it and you can fit a larger cell. Apple already made this trade-off with the iPhone 17 Pro Max — the US eSIM model (5,088 mAh) was noticeably bigger than its global counterpart (4,823 mAh). The iPhone 18 Pro Max widens that split further: 5,425 mAh for the eSIM variant (an 8.5% jump) versus 5,235 mAh for the physical-SIM model (a 6.6% gain). UK buyers on the physical-SIM version still get a meaningful upgrade, just not quite the headline number.
How it stacks up
Samsung's Galaxy S26 Ultra currently sits at 5,000 mAh and, despite matching iPhone 17 Pro Max on paper, trails it in real-world mixed-use tests. The rumored Galaxy S27 Ultra is expected to push to 5,500 mAh — which would be Samsung's first battery upgrade in the Ultra line since the Galaxy S20 Ultra back in 2020.
Chinese flagships are on a different planet entirely. The OnePlus 15 ships with 7,300 mAh and the Oppo Find X9 Pro with 7,500 mAh; both lead endurance benchmarks by a wide margin over current iPhones and Galaxy Ultras. Apple's advantage has always been software efficiency — iOS tends to squeeze more screen-on time per mAh than Android — but the raw capacity gap remains stark.
What else is coming
The iPhone 18 line is expected to launch in September 2026 alongside Apple's new A20 Pro chip, built on a 2nm process. That chip could extend battery life further regardless of cell size, which is historically how Apple has offset its capacity conservatism. The leaked figures originate from a since-deleted Weibo post, though the numbers align with earlier predictions from analyst Digital Chat Station and have been corroborated by multiple outlets, lending them reasonable credibility ahead of an official announcement.