iPhone 18 Pro battery capacity leaks: 5,400 mAh for Pro Max, stacked design for all Pros

The iPhone 18 Pro and iPhone 18 Pro Max will get substantially larger batteries than the iPhone 17 Pro generation, according to Korean supply chain sources speaking to The Elec in late May 2026. The iPhone 18 Pro is expected to use a ~4,800 mAh stacked battery (up from ~3,800 mAh on the iPhone 17 Pro), and the iPhone 18 Pro Max is expected to use a ~5,400 mAh stacked battery (up from ~4,685 mAh on the iPhone 17 Pro Max). If accurate, the Pro Max will be the first iPhone to cross the 5,000 mAh threshold.

The information comes from a single Korean supply chain source and has not been independently confirmed. The capacity numbers should be treated as "possible" until Apple announces the phones in September 2026.

What do the leaked battery numbers mean?

A 4,800 mAh battery in the iPhone 18 Pro would represent a 26% increase over the 17 Pro's ~3,800 mAh. A 5,400 mAh battery in the iPhone 18 Pro Max would represent a 15% increase over the 17 Pro Max's ~4,685 mAh. These are significant capacity jumps, especially in an industry where year-over-year gains are usually 5-10%.

The combination of larger capacity and the more efficient 2nm A20 Pro chip should produce substantial real-world battery life improvements. Ming-Chi Kuo has estimated that the iPhone 18 Pro Max will deliver 35-37 hours of video playback (vs 33 hours on the 17 Pro Max), and the iPhone 18 Pro will deliver 30-32 hours (vs 28 hours on the 17 Pro).

What is a stacked battery design?

A stacked battery is a manufacturing technique where the battery cells and the internal layers are built up in a vertical stack, rather than rolled and folded as in conventional battery designs. Stacked batteries have higher energy density (more mAh per cubic millimeter), better thermal performance (heat dissipates more evenly), and longer cycle life (the cells degrade more slowly).

Apple's first use of stacked batteries in Apple's smartwatch and the iPhone 15 Pro generation in limited form. The iPhone 18 Pro generation is the first to use stacked designs across the entire Pro lineup. The trade-off is manufacturing cost — stacked batteries are 20-30% more expensive to produce than conventional designs.

How does the iPhone 18 Pro Max compare to Android flagships?

If the 5,400 mAh capacity is accurate, the iPhone 18 Pro Max will be competitive with the largest-battery Android flagships:

• Samsung Galaxy S26 Ultra: 5,500 mAh
• OnePlus 14 Pro: 5,400 mAh
• Xiaomi 16 Pro Max: 5,500 mAh
• Google Pixel 11 Pro XL: 5,200 mAh

For years, Android flagships have offered larger batteries than the iPhone Pro Max. The iPhone 18 Pro Max's 5,400 mAh would close the gap to roughly 100-200 mAh — a small but meaningful shift.

What is still uncertain?

Three things remain unknown:

1. The exact capacity: The Elec's source gave ranges, not exact numbers. The actual capacities could be 4,600-4,900 mAh for the Pro and 5,200-5,500 mAh for the Pro Max.
2. Wired charging speeds: A larger battery is only useful if it can be charged reasonably quickly. The iPhone 18 Pro is expected to support 35W wired charging (up from 27W on the 17 Pro), but this has not been confirmed.
3. Battery life in real-world use: The 2nm A20 Pro chip is more efficient, but it also has more transistors (~20 billion vs ~18 billion on the A19 Pro). The net efficiency gain depends on real-world usage patterns, not just synthetic benchmarks.

Apple's official iPhone 18 Pro and Pro Max battery life estimates will be released in September 2026 when the phones are announced. Until then, the leaked numbers are useful for planning but not definitive.

What does this mean for the iPhone 18 base model?

The leak only covers the Pro models. The base iPhone 18 is expected to retain a similar battery capacity to the iPhone 17 (~3,561 mAh), with the gains coming from the 2nm A20 chip's improved efficiency rather than a larger battery. The iPhone Air 2, with its 5.5mm slim chassis, will likely continue to have the smallest battery in the iPhone 18 lineup (~3,200 mAh).

How does this affect buying decisions?

If you have been waiting for a Pro iPhone with substantially better battery life, the iPhone 18 Pro generation is the one to get. The 26% capacity increase on the Pro and the 15% increase on the Pro Max are the largest year-over-year battery jumps since the iPhone 11 Pro generation in 2019.

For users on iPhone 15 Pro or older, the iPhone 18 Pro is a meaningful upgrade. For users on iPhone 16 Pro or 17 Pro, the iPhone 18 Pro is a smaller upgrade — the new chip, camera, and Dynamic Island are real, but the battery life improvement alone may not justify the cost.

We will update this article when Apple announces the iPhone 18 Pro battery specifications in September 2026. Until then, treat the 4,800 mAh and 5,400 mAh figures as preliminary, sourced from a single Korean supply chain report.

What about wireless charging?

The iPhone 18 Pro and Pro Max are both expected to support 25W MagSafe wireless charging, up from 15W on the iPhone 17 Pro generation. The faster MagSafe uses the Qi2.2 standard, which doubles the previous 15W ceiling. Apple is also reportedly planning a new MagSafe charger with a longer 1.5m braided cable, sold separately for $49. The combination of larger battery and faster MagSafe means a full top-up from 0% to 100% takes roughly 90 minutes wirelessly, down from 2.5 hours on the iPhone 17 Pro. Wired charging via USB-C at 35W remains faster at roughly 70 minutes for a full charge.