iPhone 18 Pro Max Battery Leak Shows Nearly 12% Bigger Capacity

A report out of Korea claims the iPhone 18 Pro Max is getting a serious battery upgrade, with the Chinese variant reportedly reaching 5,391mAh. That would be a jump of 568mAh over the iPhone 17 Pro Max’s 4,823mAh battery in China, or roughly 11.8% more capacity. This particular number has now shown up twice, first in a regulatory filing last month and now in an alleged battery photo circulating out of Korea.

The U.S. version is rumored to go even higher, at 5,567mAh, up from 5,088mAh on the current 17 Pro Max, a gain of about 9.4%. U.S. models have consistently carried slightly bigger batteries than their Chinese counterparts because they skip the physical SIM tray entirely, and that freed-up internal space seems to be going straight into battery capacity again this year.

The regular iPhone 18 Pro isn’t getting nearly the same treatment. Reports put its battery at 4,056mAh in China and 4,288mAh in the U.S., which for the American model is only 36mAh more than the 17 Pro’s 4,252mAh, less than a 1% increase. That’s a notable gap between the two Pro models this generation, and it lines up with earlier rumors that the Pro Max could end up noticeably thicker than the standard Pro, which would explain where the extra battery room is coming from.

Bigger capacity doesn’t automatically mean bigger battery life, since actual endurance depends just as much on the display, chip efficiency, and software running on top. But if these numbers hold, buyers choosing between the two Pro models this year may be picking between a real battery upgrade and a very minor one, not just a size difference.