Apple reveals iPhone Duo battery capacity and how it compares to iPhone 18
Apple has confirmed that its first foldable smartphone, the iPhone Duo, features a 4,883mAh battery, placing it between the iPhone 18 Pro and iPhone 18 Pro Max in capacity despite its larger folding display.
The figure appeared in official European Union energy certification documents published after pre-orders opened on October 16.
Unlike conventional iPhones, the Duo uses two battery cells, rated at 2,962mAh and 1,921mAh, distributed across its folding design. Their combined capacity matches figures previously reported in leaks from China.
Apple sells the Duo exclusively with eSIM support and its C2 modem, meaning battery capacity is expected to remain consistent across international markets. Other iPhone models can have different capacities depending on whether they include a physical SIM card slot.
How does the iPhone Duo compare with other iPhones?
The Duo has one of the largest batteries in Apple’s smartphone range, surpassed only by the two most recent Pro Max generations.
Apple’s published figures and battery measurements reported by iFixit provide the following comparison:
| iPhone model | Battery capacity | Video playback |
|---|---|---|
| iPhone 18 Pro Max (eSIM) | 5,567mAh | 45 hours |
| iPhone 17 Pro Max | 5,088mAh | 39 hours |
| iPhone Duo | 4,883mAh | Up to 44 hours |
| iPhone 16 Pro Max | 4,685mAh | 33 hours |
| iPhone 18 Pro (eSIM) | 4,288mAh | 36 hours |
| iPhone 17 Pro | 4,252mAh | 33 hours |
| iPhone Air | 3,149mAh | 27 hours |
Figures based on Apple’s stated video playback estimates and reported battery capacities. The Duo’s 44-hour figure applies to its external display.
The Duo’s battery capacity is approximately 14% smaller than that of the iPhone 18 Pro Max but 14% larger than the iPhone 18 Pro.
However, its endurance depends heavily on which screen is being used. Apple estimates 44 hours of video playback on the 5.4-inch external display, falling to 31 hours on the larger 7.6-inch internal display.
The figures suggest that frequent use of the folding screen could significantly reduce battery life, despite the relatively large battery capacity. Independent battery tests will be needed to establish how the device performs under everyday conditions.
The iPhone Duo starts at $1,999 in the United States, with official sales scheduled for October 23.
Demand has already exceeded Apple’s initial online inventory, pushing estimated delivery dates for new orders into January 2027.
