Opened out, the iPhone Duo measures 164.6 mm across, which is 1.2 mm more than the 163.4 mm height of an iPhone 18 Pro Max. Closed, it covers less desk than an iPhone 18 Pro does, at 84.1 mm by 117.8 mm against 71.9 mm by 150.0 mm.
Those two facts come from the same set of numbers and pull in opposite directions, which is the point of the shape. Apple describes the open iPhone Duo as a wide, passport-like format, and the dimensions show what that costs and what it buys.
Key facts: iPhone Duo against both iPhone 18 Pro sizes
| Measurement | iPhone Duo | iPhone 18 Pro | iPhone 18 Pro Max |
|---|---|---|---|
| Width | 164.6 mm open, 84.1 mm closed | 71.9 mm | 78.0 mm |
| Height | 117.8 mm open and closed | 150.0 mm | 163.4 mm |
| Thickness | 5.2 mm open, 11.3 mm closed | 8.75 mm | 8.75 mm |
| Weight | 254 g | 211 g | 249 g |
| Main display | 7.6-inch inner, 1878 by 2670 | 6.3-inch, 2622 by 1206 | 6.9-inch, 2868 by 1320 |
| Second display | 5.4-inch outer, 1398 by 2034 | None | None |
| Price from | $1,999 | $1,199 | $1,299 |
| Arrives | October 23 | September 18 | September 18 |
Open, it is wider than a Pro Max is tall
The open width of 164.6 mm is the single number that tells you how different this phone is in the hand. It exceeds the long dimension of the largest iPhone Apple sells, and it does so while the phone is only 5.2 mm thick.
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The height is the surprise in the other direction. At 117.8 mm the open Duo is 32.2 mm shorter than an iPhone 18 Pro and 45.6 mm shorter than a Pro Max, so it is a wide, short rectangle rather than a scaled-up phone.
That is what makes the format passport-like rather than tablet-like. Nothing in the Duo’s open footprint is longer than a current iPhone; it is only wider.
The open face is about half again the area of a Pro Max front
Multiply Apple’s published figures and the open Duo presents roughly 194 square centimeters of face, against about 127 for the iPhone 18 Pro Max and about 108 for the iPhone 18 Pro. That is about 1.5 times a Pro Max and about 1.8 times a Pro.
The ratio lines up with Apple’s own display claim, which is that the 7.6-inch inner display is 50 percent larger than the iPhone 18 Pro Max display. Body area and display area are different measurements, so the agreement is a sanity check rather than proof of either.
| Device and state | Face dimensions | Face area, arithmetic on Apple’s figures |
|---|---|---|
| iPhone Duo, open | 164.6 by 117.8 mm | About 194 sq cm |
| iPhone Duo, closed | 84.1 by 117.8 mm | About 99 sq cm |
| iPhone 18 Pro | 150.0 by 71.9 mm | About 108 sq cm |
| iPhone 18 Pro Max | 163.4 by 78.0 mm | About 127 sq cm |
| iPhone Air | 156.2 by 74.7 mm | About 117 sq cm |
Closed, it covers less surface than an iPhone 18 Pro
The closed footprint is about 99 square centimeters, roughly 8 percent less than the iPhone 18 Pro and about 22 percent less than the Pro Max. A folded Duo occupies less of a pocket opening than either Pro, in two dimensions out of three.
The third dimension is where it pays. Closed thickness is 11.3 mm against 8.75 mm for both Pro models, and the weight is 254 grams against 211 and 249, as the Duo against the Pro Max comparison lays out.
Closed, then, the trade is a shorter, wider, thicker block. Whether that suits a given pocket is not something any spec sheet settles, and nobody outside Apple has carried one.
The height never changes, and the aspect ratio follows
Apple lists 117.8 mm as the height in both states, so the fold runs across the width and the top and bottom edges stay put. Only the width halves, from 164.6 mm to 84.1 mm.
Apple says both displays share the same aspect ratio, and that the 5.4-inch outer panel has more than 90 percent of the screen area of an iPhone 18 Pro. That is the closed-state consolation: a cover screen close in size to a current Pro, on a body shorter than one, a distinction worth weighing alongside the usual Pro against Pro Max question.
What Apple has not said
Apple has published no display area in square units, no bezel measurement, no camera housing height, and no figure for how much the phone stands proud of a flat surface. Nor has it published a fold-cycle rating or repair pricing for anything in our event recap.
The area figures above are arithmetic on Apple’s published dimensions rather than numbers Apple states. Pre-orders open Friday, October 16 at 5 a.m. PT, with availability from Friday, October 23 in more than 70 countries and regions and 28 more on Friday, October 30.
