iPhone 18 Pro Max Battery Capacity Leaks — and It Would Beat the Galaxy S26 Ultra

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iPhone 18 Pro Max Battery Capacity Leaks — and It Would Beat the Galaxy S26 Ultra


Apple has never been known for big battery numbers – as most of us know – but this could change this September. A new leak from tipster @fireuniverse8 on X claims the iPhone 18 Pro Max will carry the largest battery ever fitted in a non-folding iPhone — and depending on which version you buy, the number could be either at 5,235mAh or 5,425mAh.
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Summary

  • Two battery sizes, one phone: The eSIM-only model gets 5,425mAh. The physical SIM version gets 5,235mAh — the same split Apple used in the iPhone 17 Pro Max.
  • Biggest jump in years: The physical SIM model gains 412mAh over the iPhone 17 Pro Max’s 4,823mAh. The eSIM version adds 337mAh over the 17 Pro Max’s 5,088mAh.
  • Beats the Galaxy S26 Ultra: Samsung’s flagship flagship packs a 5,000mAh cell. Both iPhone 18 Pro Max variants clear that number.
  • Source carries caveats: @fireuniverse8 has a mixed track record — treat this as directional, not confirmed.
  • Context: Prior leaks had already pointed to a record battery; this is the first time exact figures have been named.

The Numbers in Context

The gap between the two versions exists because eSIM-only iPhones physically remove the SIM card tray and antenna components, freeing up internal space for a slightly larger battery cell. Apple introduced this split with the iPhone 17 Pro Max, and this leak suggests it continues for the 18 Pro Max.

Both figures represent a meaningful step forward. The iPhone 17 Pro Max with a physical SIM had a 4,823mAh battery — a number most Android flagship owners would consider modest. A jump to 5,235mAh is 412mAh more, which translates to roughly 8–10% more capacity depending on efficiency. The eSIM version’s gain of 337mAh over 5,088mAh is proportionally smaller but still significant at this size class.

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Why Beating the S26 Ultra Actually Matters

The Samsung Galaxy S26 Ultra has a 5,000mAh battery. In the past, Apple has never come close to matching Samsung’s Pro Max rival on raw capacity. If this leak is accurate, the iPhone 18 Pro Max flips that comparison entirely — the physical SIM model clears Samsung’s number by 235mAh, and the eSIM version beats it by 425mAh. For years, iPhone buyers who wanted the best battery life on iOS had to accept a smaller cell than their Android counterparts. That dynamic appears to be ending.

I suppose the honest framing is this: bigger capacity doesn’t automatically mean better real-world life. Apple’s software efficiency and chip architecture have historically outperformed Android phones with larger cells on actual screen-on time. A 5,235mAh iPhone 18 Pro Max running A20 Pro silicon could be a genuinely remarkable endurance device — or it could simply match what the 4,823mAh iPhone 17 Pro Max already delivered. The test will come in reviews.

What This Doesn’t Tell Us

No wired charging speed has leaked. Apple has stayed at 30W wired for the Pro Max line while Android flagships race toward 120W and beyond. A bigger cell charged at 30W takes longer to top up, which is the one trade-off a capacity upgrade doesn’t automatically fix. Wireless charging and reverse wireless charging specs are also unconfirmed. The full picture won’t emerge until Apple’s September event.