Closed, the iPhone Duo is 117.8 mm (4.64 in) tall, 84.1 mm (3.31 in) wide and 11.3 mm (0.44 in) thick. Opened, it is 164.6 mm (6.48 in) wide and only 5.2 mm (0.21 in) thin, and it weighs 254 grams (8.96 oz) either way. That makes the closed phone shorter than an iPhone 18 Pro but wider and thicker, and the open phone about as wide as an iPhone 18 Pro Max is tall. Apple's first foldable iPhone went on sale in the US on October 23, 2026, starting at $1,999.
All measurements below come from Apple's iPhone Duo tech specs and the iPhone 18 Pro specs, unless a line says it is our own calculation. Product photos: Apple.
iPhone Duo dimensions, open and closed
| Phone | Height | Width | Depth | Weight |
|---|---|---|---|---|
| iPhone Duo, closed | 117.8 mm (4.64 in) | 84.1 mm (3.31 in) | 11.3 mm (0.44 in) | 254 g (8.96 oz) |
| iPhone Duo, open | 117.8 mm (4.64 in) | 164.6 mm (6.48 in) | 5.2 mm (0.21 in) | 254 g (8.96 oz) |
| iPhone 18 Pro | 150.0 mm (5.91 in) | 71.9 mm (2.83 in) | 8.75 mm (0.34 in) | 211 g (7.44 oz) |
| iPhone 18 Pro Max | 163.4 mm (6.43 in) | 78.0 mm (3.07 in) | 8.75 mm (0.34 in) | 249 g (8.78 oz) |
Apple notes that size and weight vary by configuration and manufacturing process, so expect small differences between units. To see any of these in other units, the Unit Converter converts millimeters, inches and grams.
How big is the iPhone Duo in your hand?
Compared with the phones most people already know:
- Closed, it is a short, wide phone. It is 32 mm shorter than an iPhone 18 Pro and 12 mm wider. It is 2.55 mm thicker than either Pro model, because it is two thin halves stacked together.
- It is not much heavier than a Pro Max. At 254 grams it weighs 5 grams more than the iPhone 18 Pro Max and 43 grams more than the iPhone 18 Pro.
- Open, it is a small tablet. The open width, 164.6 mm, is slightly more than the height of an iPhone 18 Pro Max (163.4 mm), so the open Duo is roughly a Pro Max turned sideways, but 4.64 inches tall instead of 3.07 inches wide.
- Open, it is very thin. At 5.2 mm, the unfolded phone is well under the 8.75 mm of an iPhone 18 Pro.
iPhone Duo screen size and resolution
The Duo has two screens: a large inner one that you see when it is open, and a smaller outer one for use when it is closed.
| Inner display | Outer display | |
|---|---|---|
| Size (rounded corners) | 7.6 inches | 5.4 inches |
| Size as a standard rectangle | 7.58 inches | 5.36 inches |
| Resolution | 1878 × 2670 pixels | 1398 × 2034 pixels |
| Pixel density | 430 ppi | 460 ppi |
| Approximate screen area (our calculation) | 6.21 × 4.37 in (158 × 111 mm) | 4.42 × 3.04 in (112 × 77 mm) |
| Shape (our calculation) | about 1.42 : 1 | about 1.45 : 1 |
Apple says the inner display is 50 percent larger than the iPhone 18 Pro Max screen, and the outer display gives 90 percent of the screen area of an iPhone 18 Pro. Both screens are OLED, support ProMotion up to 120Hz and the Always-On display, and have the Dynamic Island, according to Apple's specs page.
We worked out the physical screen size by dividing each pixel count by its pixel density. For example, 2670 pixels at 430 pixels per inch is 6.21 inches, and the diagonal of 6.21 by 4.37 inches comes to 7.59 inches, which matches Apple's 7.58-inch figure. The inner screen's shape is close to the 1.414 ratio of A4 paper, so it is noticeably squarer than a regular phone screen. That matters for video: a 16:9 movie on the open Duo fills the width and leaves bars above and below. The Aspect Ratio Calculator shows how any video or photo fits a given screen.
iPhone Duo wallpaper size
To make a wallpaper that fills each screen without blurring, start from an image at least as large as that screen's resolution:
- Inner display: 1878 × 2670 pixels.
- Outer display: 1398 × 2034 pixels.
Steps:
- Pick a photo larger than the target size. A photo from a recent phone camera is big enough.
- Crop it to the screen's shape with the Image Crop tool. Enter the exact pixel size, or use the Aspect Ratio Calculator to find a crop that keeps the shape.
- If the crop is still larger than the screen, shrink it to the exact size with the Image Resizer.
- Keep faces and text away from the top center, where the Dynamic Island sits, and leave a little margin around the edges, because iOS lets you move and scale a wallpaper when you set it.
If your photos are in HEIC format and an app will not open them, the HEIC to JPG converter handles that in your browser. Our guide to HEIC files explains the format.
iPhone Duo price, storage and colors
According to Apple's announcement and its online store, the US prices are:
| Storage | US price |
|---|---|
| 256GB | $1,999 |
| 512GB | $2,199 |
| 1TB | $2,599 |
| 2TB | $3,199 |
It comes in two colors, star white and night sky. In the US it went on sale on October 23, 2026, at apple.com and select carriers. Apple says it reaches 28 more countries and regions on Friday, October 30. Prices differ by country.
Other specifications worth knowing
- Chip: A20 Pro, the same chip as the iPhone 18 Pro models.
- Battery: one battery in each half.
- Build: grade 5 titanium.
- Water and dust: rated IP68, tested to a depth of 6 meters for up to 30 minutes. Apple notes that this resistance is not permanent and can decrease with normal wear.
Common questions
Is the iPhone Duo bigger than the iPhone 18 Pro Max? Closed, no: it is 45.6 mm shorter, though 6.1 mm wider and 2.55 mm thicker. Open, its 7.6-inch inner screen is larger than the Pro Max's 6.9-inch screen; Apple says it has 50 percent more screen.
How heavy is the iPhone Duo? 254 grams (8.96 ounces), open or closed. That is 5 grams more than the iPhone 18 Pro Max.
How thick is the iPhone Duo? 11.3 mm (0.44 inch) closed and 5.2 mm (0.21 inch) open.
What is the iPhone Duo screen resolution? The inner display is 1878 × 2670 pixels at 430 ppi, and the outer display is 1398 × 2034 pixels at 460 ppi.
When can I buy the iPhone Duo outside the US? Apple says it arrives in 28 more countries and regions on October 30, 2026.