
Summary
- 4,883mAh total, dual-cell design: One 1,921mAh cell and one 2,962mAh cell — split across the two halves of the foldable chassis, standard for book-style foldables.
- Smaller than expected: Earlier leaks had pointed to a 5,400–5,800mAh battery for the iPhone Ultra. This figure is well below that.
- Smaller than the iPhone 18 Pro Max: The Pro Max is tipped for 5,235–5,425mAh depending on SIM configuration. The Ultra has less battery despite needing to power two displays.
- Sits between Galaxy Z Fold 7 and Pixel 10 Pro Fold: Samsung’s Fold 7 has 4,400mAh; Google’s Pixel 10 Pro Fold has 5,015mAh. The Ultra lands in between.
- September launch remains on track: DCS separately confirmed the iPhone Ultra is already in production, with a September announcement alongside the iPhone 18 Pro models.

Why This Number Is Complicated
The downward revision from 5,800mAh to 4,883mAh appears to reflect real engineering trade-offs. A foldable chassis has a hinge mechanism, folding display layers, and a thinner profile — all of which compress the available volume for battery cells. Ming-Chi Kuo had previously indicated Apple would use high-density battery cells to compensate, which may help close the efficiency gap even if the raw number looks modest.
The iPhone 18 Pro Max Comparison
Here’s the uncomfortable comparison. The iPhone 18 Pro Max — a conventional slab phone — is tipped for 5,391–5,567mAh depending on SIM configuration. The iPhone Ultra, at $2,000+ and dual-display, carries a smaller cell. That’s not necessarily fatal — Apple’s A20 chip efficiency and iOS power management have consistently outperformed Android rivals with larger batteries on screen-on time. But it’s a question that reviewers will answer definitively in September.

