The iPhone Duo has two displays with two resolutions: 1878 by 2670 pixels on the 7.6-inch inner panel and 1398 by 2034 pixels on the 5.4-inch outer one, according to Apple’s tech specs. The inner display runs at 430 pixels per inch and the outer at 460 ppi, and Apple’s product page says both share the same aspect ratio.
Those numbers are unlike any previous iPhone, which is why the shape matters as much as the size. The 6.3-inch iPhone 18 Pro is 2622 by 1206, a tall 19.5:9 rectangle. The Duo’s panels are far squarer, which Apple describes as a wide, passport-like format when open. Our iPhone Duo guide covers the phone as a whole; this piece is about the pixels.
iPhone Duo display resolutions, with the 18 Pro for scale
Here are Apple’s published figures for the Duo’s two panels next to the two iPhone 18 Pro sizes, with the pixel counts and aspect ratios worked out from them.
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| Display | Size | Resolution | Pixel density | Total pixels | Long side divided by short side |
|---|---|---|---|---|---|
| iPhone Duo, inner | 7.6-inch | 1878 x 2670 | 430 ppi | 5,014,260 | 1.42 |
| iPhone Duo, outer | 5.4-inch | 1398 x 2034 | 460 ppi | 2,843,532 | 1.45 |
| iPhone 18 Pro | 6.3-inch | 2622 x 1206 | 460 ppi | 3,162,132 | 2.17 |
| iPhone 18 Pro Max | 6.9-inch | 2868 x 1320 | 460 ppi | 3,785,760 | 2.17 |
The inner display: 1878 by 2670 at 430 ppi
Multiply 1878 by 2670 and you get 5,014,260 pixels, about 32 percent more than the Pro Max’s 3,785,760. Apple’s larger claim, that the inner display is 50 percent bigger than the Pro Max’s, is about area rather than pixels, and the ppi figure explains the gap. At 430 ppi, 1878 pixels is about 4.37 inches and 2670 pixels is about 6.21 inches, which is roughly 27.1 square inches. The Pro Max at 460 ppi is about 2.87 by 6.24 inches, or 17.9 square inches, and 27.1 divided by 17.9 is about 1.52.
The diagonal checks out too. The square root of 4.37 squared plus 6.21 squared is about 7.59 inches, which Apple rounds to 7.6. Apple says this is the largest and thinnest iPhone display ever, with a nano-texture finish to cut glare and hide the crease, covered by a custom polymer Apple says is 40 percent stiffer than the industry standard over high-strength glass.
The outer display: 1398 by 2034 at 460 ppi
The outer panel is 1398 by 2034, which is 2,843,532 pixels, at the same 460 ppi Apple uses on the 18 Pro. That works out to about 3.04 by 4.42 inches, or 13.4 square inches. The 6.3-inch 18 Pro display is about 2.62 by 5.70 inches, or 14.9 square inches, and 13.4 divided by 14.9 is about 0.90, which matches Apple’s claim that the outer display has more than 90 percent of the screen area of the iPhone 18 Pro.
In other words, the closed Duo gives you nearly as much screen as the 18 Pro but in a much shorter, wider shape, with the same sharpness. Both Duo panels share the rest of their spec sheet: ProMotion up to 120Hz, Always-On, 1000 nits typical, 1600 nits peak HDR, 3000 nits peak outdoor and a 2,000,000:1 contrast ratio, per Apple’s tech specs.
Why both displays share one aspect ratio
Divide the long side by the short side and the inner display comes out at 2670 over 1878, or about 1.42, while the outer is 2034 over 1398, or about 1.45. Both are close to 10:7, which is 1.43, and within about 2 percent of each other. Apple’s product page describes them as the same aspect ratio; Apple has not said how it defines that figure, and rounded corners and the folding cover mean the active area does not map exactly onto the pixel grid.
The reason it matters is software. Apple says iOS 27 on the Duo uses layouts that adapt as the phone opens and closes and as it is posed, and a matched shape means an app framed on the outer display can scale up to the inner one without changing its proportions. Content is enlarged rather than re-cropped, which is the whole point of a phone that spends part of its day closed.
- Inner: 2670 divided by 1878 is about 1.42
- Outer: 2034 divided by 1398 is about 1.45
- iPhone 18 Pro: 2622 divided by 1206 is about 2.17
Compared with the 18 Pro’s 2.17, both Duo panels are a different kind of screen, which is why Apple built Split View for the inner display. The Duo goes on sale Friday, October 23, from $1,999. Our iPhone Duo vs iPhone 18 Pro Max comparison and iPhone 18 Pro guide have the other side of the display argument.
