The iPhone Duo is nearly as long as the iPhone 18 Pro Max when open, but it is much wider: it unfolds into a 7.6-inch display, then folds down to a compact 3.31-inch-wide body. Apple lists the Duo at 254 grams, just 5 grams heavier than the Pro Max.
Why the video makes them look almost the same length
In the side-by-side video described by 9to5Mac, the Duo is open with its long edge aligned to the Pro Max’s long edge. That visual comparison is supported by Apple’s dimensions: the Duo is 6.48 inches wide when open, while the Pro Max is 6.43 inches tall. The difference is just 0.05 inch.
The similar length does not mean the phones occupy similar space when open. The Duo’s other open dimension is 4.64 inches, giving it a much broader, tablet-like shape. The Pro Max remains a 3.07-inch-wide slab.
iPhone Duo and iPhone 18 Pro Max dimensions
| Measurement | iPhone Duo | iPhone 18 Pro Max |
|---|---|---|
| Open body dimensions | 6.48 × 4.64 × 0.21 inches | Not applicable; single-slab body (Apple, 2026) |
| Closed body dimensions | 3.31 × 4.64 × 0.44 inches | 3.07 × 6.43 × 0.34 inches |
| Display | 7.6-inch inner OLED; 5.4-inch outer display | 6.9-inch OLED |
| Weight | 254 grams | 249 grams |
Dimensions, display sizes and weights are Apple’s published 2026 specifications: iPhone Duo specifications and iPhone 18 Pro Max specifications.
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- This phone is unlocked and compatible with any carrier of choice on GSM and CDMA networks (e.g. AT&T, T-Mobile, Sprint, Verizon, US Cellular, Cricket, Metro, Tracfone, Mint Mobile, etc.).
- Please check with your carrier to verify compatibility.
- When you receive the phone, insert a SIM card from a compatible carrier. Then, turn it on, connect to Wi-Fi, and follow the on screen prompts to activate service.
- The device does not come with headphones or a SIM card. It does include a generic (Mfi certified) charger and charging cable.
- Tested for battery health and guaranteed to have a minimum battery capacity of 80%.
What changes when the Duo folds
Folded, the Duo measures 3.31 inches wide and 4.64 inches high. It is wider than the Pro Max’s 3.07-inch body, but its folded height is substantially shorter than the Pro Max’s 6.43 inches. At 0.44 inch thick, it is also thicker than the Pro Max’s 0.34-inch slab.
The Duo’s two configurations suit different tasks: its 5.4-inch outer display is available while closed for quick, phone-style use; opening it reveals the 7.6-inch inner panel. The Pro Max has one 6.9-inch display and does not change form.
Rank #2
- This phone is unlocked and compatible with any carrier of choice on GSM and CDMA networks (e.g. AT&T, T-Mobile, Sprint, Verizon, US Cellular, Cricket, Metro, Tracfone, Mint Mobile, etc.).
- Please check with your carrier to verify compatibility.
- When you receive the phone, insert a SIM card from a compatible carrier. Then, turn it on, connect to Wi-Fi, and follow the on screen prompts to activate service.
- The device does not come with headphones or a SIM card. It does include a generic (Mfi certified) charger and charging cable.
- Tested for battery health and guaranteed to have a minimum battery capacity of 80%.
How much larger is the Duo’s screen?
Apple lists the Duo’s inner display at 7.6 inches diagonally and the Pro Max display at 6.9 inches. The larger diagonal means the Duo offers more display canvas when open, but it does not make every video or app appear proportionally larger. What fits on screen depends on aspect ratio, orientation, cropping, rounded corners and the foldable’s hinge area.
Ryan Christoffel of 9to5Mac describes the Duo as having “the largest display ever in an iPhone, bigger even than iPhone 18 Pro Max.” That refers to the Duo’s open inner display; it does not describe the closed outer screen.
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- This phone is unlocked and compatible with any carrier of choice on GSM and CDMA networks (e.g. AT&T, T-Mobile, Sprint, Verizon, US Cellular, Cricket, Metro, Tracfone, Mint Mobile, etc.).
- Please check with your carrier to verify compatibility.
- When you receive the phone, insert a SIM card from a compatible carrier. Then, turn it on, connect to Wi-Fi, and follow the on screen prompts to activate service.
- The device does not come with headphones or a SIM card. It does include a generic (Mfi certified) charger and charging cable.
- Tested for battery health and guaranteed to have a minimum battery capacity of 80%.
Which design is easier to carry?
- For a slim, conventional phone: The Pro Max is narrower and thinner as a single slab.
- For a larger screen that can fold away: The Duo closes to a shorter 4.64-inch-high body and opens to a 7.6-inch display.
- For weight-conscious buyers: The Duo weighs 254 grams, compared with 249 grams for the Pro Max—a 5-gram difference in Apple’s 2026 specifications.
Apple also lists support for Apple Pencil (USB-C) on the Duo, a capability that complements its larger open display.
Quick Recap
Best Value
- This phone is unlocked and compatible with any carrier of choice on GSM and CDMA networks (e.g. AT&T, T-Mobile, Sprint, Verizon, US Cellular, Cricket, Metro, Tracfone, Mint Mobile, etc.).
- Please check with your carrier to verify compatibility.
- When you receive the phone, insert a SIM card from a compatible carrier. Then, turn it on, connect to Wi-Fi, and follow the on screen prompts to activate service.
- The device does not come with headphones or a SIM card. It does include a generic (Mfi certified) charger and charging cable.
- Tested for battery health and guaranteed to have a minimum battery capacity of 80%.
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