iPhone 18 Pro Max battery size reportedly leaks: 5,425 mAh (eSIM) and 5,235 mAh (physical SIM)

The iPhone 18 Pro Max will ship with a substantially larger battery than the 17 Pro Max, according to a Macworld report published on July 2 2026. The report, which Macworld sourced to "social media posts that are hard to trace to their original source," puts the eSIM version of the iPhone 18 Pro Max at 5,425 mAh and the physical-SIM version at 5,235 mAh.

For context, the iPhone 17 Pro Max ships with a 5,088 mAh cell on the eSIM-only model and 4,823 mAh on the physical-SIM model. If the new numbers hold, the iPhone 18 Pro Max will gain roughly 337 mAh (eSIM) and 412 mAh (physical SIM) - about a 6.6% and 8.5% bump respectively, before counting any efficiency gains from the A20 Pro chip.

The 9to5Mac write-up that surfaced the Macworld piece is explicit about the sourcing limits: "This report, however, has questionable sourcing. It points to a variety of social media posts that are hard to trace to their original source."

Why the timing matters

The leak's timing lines up with the recent data breach at Tata Electronics, one of Apple's largest iPhone assembly partners. The Register and other outlets have reported that internal Tata documents surfaced in late June 2026, and that subsequent leaks from that breach "show all signs of being legitimate." 9to5Mac's Ryan Christoffel floats the possibility that the new battery numbers originated with the Tata breach, though he notes that "we don't know if these battery numbers originated with the Tata breach."

That is the strongest argument for taking the leak seriously: capacity numbers, supplier names and tooling references tied to a single breach tend to share provenance.

Where this fits in the battery story

A separate leak reported in late May 2026 by Korean outlet The Elec had the iPhone 18 Pro Max at around 5,400 mAh with a stacked battery design. The Macworld number (5,425 mAh for the eSIM model) is within 25 mAh of that figure - a near miss, not a contradiction. Stacked batteries allow higher energy density, which is consistent with the Pro Max gaining capacity without making the chassis meaningfully thicker.

For the smaller iPhone 18 Pro, the Elec leak pointed to roughly 4,800 mAh, and Apple is widely expected to bring the stacked design to the entire 18 Pro lineup, not just the Max.

Update (July 6): regulatory filings point to an even larger cell

Since this article first published, a set of figures attributed to regulatory filings has circulated with higher — and region-split — numbers, as compiled in MacRumors' iPhone 18 Pro roundup:

Model	US (eSIM)	China (physical SIM)
iPhone 18 Pro	4,288 mAh	4,056 mAh
iPhone 18 Pro Max	5,567 mAh	5,391 mAh

The US models are eSIM-only, which frees the internal space a physical-SIM tray would otherwise occupy — the reported reason the China variants come in smaller. The 5,567 mAh figure for the US Pro Max is about 142 mAh above the earlier social-media leak of 5,425 mAh, and about 479 mAh (roughly 9.4%) over the 17 Pro Max's 5,088 mAh eSIM cell.

The two reports do not cancel out — a filing-derived number carries more weight than an untraceable social post, and both land in the same 5,400-5,600 mAh band. The most likely explanation is that the social-media leak was an earlier or lower-SKU estimate. We are keeping overall confidence at "possible" until Apple ships the phone, but the regulatory figures are the stronger data point of the two.

How big a deal is the bump?

In raw capacity terms, a 6-8% jump sounds modest, but it lands on top of the A20 Pro's expected efficiency gains from the move to TSMC's 2nm N2 process and the new WMCM (Wafer-Level Multi-Chip Module) packaging. Ming-Chi Kuo has previously estimated that the iPhone 18 Pro Max will deliver 35-37 hours of video playback versus 33 hours on the 17 Pro Max, and the iPhone 18 Pro 30-32 hours versus 28 on the 17 Pro.

If the new leak is correct, the Pro Max could plausibly push past the 38-hour mark for video playback, putting the largest iPhone within striking distance of the 40-hour threshold Apple has reportedly targeted internally.

What is still uncertain

Three things keep this leak at the "possible" confidence level rather than "credible":

1. The original source is unverified social media posts. Macworld and 9to5Mac both flag the chain of custody.
2. Apple has historically had multiple battery SKUs per device (one for each production line, region and supplier), and we do not know which SKU these numbers correspond to.
3. The numbers could be an early engineering target rather than the final shipping spec. Apple has been known to swap cells as late as EVT (Engineering Validation Test) if a supplier improves yield or hits a thermal problem.

We will move this to "credible" if a second independent supply-chain source confirms the 5,425 / 5,235 mAh figures before mass production starts in August 2026.

What to do if you are buying

If you were already planning to upgrade to the iPhone 18 Pro Max for battery life, this leak does not change the calculus - it slightly strengthens it. If you were on the fence because the 17 Pro Max was already good enough, the answer is the same as it has been: wait for the first independent teardown in late September 2026 to confirm the actual shipping cell.

Apple is expected to unveil the iPhone 18 Pro Max on September 8 or 9 2026, with shipping starting September 19.