Phone Size and Weight Comparison
| iPhone 18 Pro | iPhone 18 Pro Max | iPhone Duo closed | iPhone Duo open | |
| Height | 5.91 in | 6.43 in | 4.64 in | 4.64 in |
| Width | 2.83 in | 3.07 in | 3.31 in | 6.48 in |
| Thickness | 0.34 in | 0.34 in | 0.44 in | 0.21 in |
| Weight | 7.44 oz / 211 g | 8.78 oz / 249 g | 8.96 oz / 254 g | same |
| Display | 6.3″ | 6.9″ | 5.4″ | 7.6″ |
Screen size is more important than the diagonal
Using Apple’s pixel dimensions and measured rectangular diagonals, the approximate physical display dimensions are:
| Display | Approx. screen W × H | Screen area |
| 18 Pro 6.3″ | 2.62 × 5.70″ | 14.9 sq in |
| 18 Pro Max 6.9″ | 2.87 × 6.23″ | 17.9 sq in |
| Duo outer 5.4″ | 3.04 × 4.42″ | 13.4 sq in |
| Duo inner 7.6″ | 4.36 × 6.20″ | 27.0 sq in |
These dimensions are calculated from Apple’s stated diagonals and resolutions, so they are approximate. Apple says the Duo’s open screen provides about 50% more display area than the 18 Pro Max, at the same weight.
Closed, however, the Duo is a very different shape. It’s 1.79 inches shorter than the Pro Max and 0.24 inch wider and 29% thicker. Think of it less as a tall phone and more as a small, thick passport-sized device. Apple itself describes it as similar in size to a passport when closed.
More Specs
| iPhone 18 Pro | iPhone 18 Pro Max | iPhone Duo | |
| Video playback | 36 hr | 45 hr | 31 hr / 44 hr |
| Streamed video | 33 hr | 40 hr | 26 hr / 37 hr |
| Rear cameras | 3 × 48 MP | 3 × 48 MP | 2 × 48 MP |
| Telephoto | 48 MP | 48 MP | None |
| Ultra-wide | 48 MP | 48 MP | 48 MP |
| Main camera | 48 MP variable aperture | 48 MP variable aperture | 48 MP |
| Folded width | 71.9 mm | 78.0 mm | 84.1 mm |
| Folded height | 150.0 mm | 163.4 mm | 117.8 mm |
Battery: Pro Max wins, but Duo is close
18 Pro Max
- 45 hr local video
- 40 hr streaming
Duo
- 44 hr using the small outer display
- 31 hr using the large inner display
- 37 hr streaming on outer display
- 26 hr streaming on inner display
18 Pro
- 36 hr local video
- 33 hr streaming
The Duo has excellent battery life when used mostly as a conventional folded phone. And opening that enormous 7.6-inch display extracts a substantial battery penalty.
Cameras: Pro and Pro Max clearly beat Duo
The 18 Pro and Pro Max have the same basic Pro Fusion camera system:
- 48 MP main with variable aperture
- 48 MP ultra-wide
- 48 MP telephoto
- 0.5×, 1×, 2× plus true telephoto capability
- More sophisticated optical image stabilization
The Duo has:
- 48 MP main
- 48 MP ultra-wide
- 0.5×, 1× and sensor-crop 2×
- No dedicated telephoto
For normal snapshots, the Duo should be excellent. The absence of the telephoto may be significant. A 2× crop from a 48 MP sensor is useful, but it isn’t a substitute for the Pro’s dedicated 48 MP telephoto.
Thickness: Duo is both thinnest and thickest
An interesting engineering tradeoff:
18 Pro / Max:
8.75 mm
Duo opened:
5.2 mm
Duo folded:
11.3 mm
So each half of the Duo is extraordinarily thin. But that’s irrelevant when it’s sitting in your pocket because you’ll normally carry it folded, where it is approximately 29% thicker than an 18 Pro.
Pocketability
18 Pro: 150 × 71.9 × 8.75 mm, 211 g
This is easily the most pocketable. It’s narrower, thinner and about 43 g lighter than the Duo.
18 Pro Max: 163.4 mm tall and 249 g
Its disadvantage is length. It occupies a lot of vertical pocket space and can be awkward when sitting.
Duo: 117.8 × 84.1 × 11.3 mm, 254 g folded
- 28% shorter than Pro Max
- wider
- thicker
- essentially the same weight as the Pro Max
For a front pants pocket, the Duo’s 84-mm width and 11.3-mm thickness will be more noticeable than its weight. But its short 118-mm height could actually make it more comfortable while sitting.
Ranking
| Priority | Best |
| Pocketability | 🥇 18 Pro |
| Battery | 🥇 18 Pro Max |
| Camera | 🥇 18 Pro / Pro Max |
| Reading/web | 🥇 Duo |
| Maps/travel planning | 🥇 Duo |
| Reviewing photographs | 🥇 Duo |
| Taking photographs | 🥇 18 Pro / Max |
| One-handed use | 🥇 18 Pro |
| Maximum screen in pocket | 🥇 Duo by far |
Decision Tree
I’d eliminate the 18 Pro Max unless maximum battery life is paramount. That leaves two genuinely different choices:
18 Pro = camera-first phone.
You get the full Pro camera system in a substantially lighter, thinner, more pocketable package.
Duo = computer-first phone.
You sacrifice the telephoto camera and some pocketability in exchange for a 7.6-inch display that provides roughly 50% more display area than the Pro Max.
Another Option: Duo vs iPad mini
| iPhone Duo open | iPad mini | |
| Display | 7.6″ OLED | 8.3″ LCD |
| Approx. screen dimensions | 4.37 × 6.22″ | 4.56 × 6.94″ |
| Approx. screen area | 27.2 in² | 31.6 in² |
| Resolution | 1878 × 2670 | 1488 × 2266 |
| Pixel density | 430 ppi | 326 ppi |
| Refresh rate | 1-120 Hz ProMotion | 60 Hz |
| Outdoor peak brightness | 3,000 nits | 500 nits |
| HDR | Yes | No |
| Device weight | 254 g | 293 g Wi-Fi |
| Thickness | 5.2 mm open | 6.3 mm |
| Folded size | 117.8 × 84.1 mm | 195.4 × 134.8 mm |
| Folded thickness | 11.3 mm | 6.3 mm |
| Pencil | USB-C Pencil | Pencil Pro + USB-C Pencil |
Screen size
The iPad mini’s 8.3-inch specification sounds substantially larger than the Duo’s 7.6 inches. It isn’t. Calculated from the resolution/aspect ratios:
iPad mini: ~31.6 square inches
Duo: ~27.2 square inches
So the Duo provides about 86% of the iPad mini’s physical screen area.
More importantly, the Duo pixel density is much greater than the Mini at 420 vs 326 ppi. Thus the Duo screen resolution is 1878 x 2670 vs the Mini at 1488 x 2266.
Apple Pencil
May be a Mini victory? The Duo supports the USB-C Apple Pencil, and the mini supports Apple Pencil Pro as well as the USB-C Pencil. But the Duo has the nano-texture screen which many find superior when using the pen.
Portability changes everything
iPad mini is not ‘pocketable’ at195 × 135 × 6.3 mm, 293 g
Duo folded, thicker but smaller length and width: 118 × 84 × 11.3 mm, 254 g
Could the Duo replace your iPad mini?
The key number is 86%. You’re getting roughly 86% of the mini’s screen area in something that folds into your pocket and is already your phone. And the Duo display is technologically far superior: OLED, HDR, 120-Hz ProMotion, much higher pixel density and vastly greater outdoor brightness.
Personally, I’d much rather carry an iPhone Duo + MacBook than an iPhone 18 Pro + iPad mini + MacBook. And I’m keeping my current iPhoneAir which, with easy eSIM switching, I can use when I want something really light and easy to carry.
