Closed, the iPhone Duo is a 5.4-inch phone, the same diagonal as the iPhone 13 mini. Open, it's a 7.6-inch display that Apple's announcement sizes at 50 percent larger than the iPhone 18 Pro Max's. Both phones launched at the September 9 event with the same A20 Pro inside, so the gap between the iPhone 18 Pro and the Duo lives in the body and the camera bump.
Small phones died too soon, and I didn't expect a foldable to be what brings a mini-sized screen back. It does it inside the heaviest phone of the three.
Where they split
| iPhone 18 Pro | iPhone Duo | Difference | |
|---|---|---|---|
| Display (Pro / Max) | 6.3 in / 6.9 in | 7.6 in open, 5.4 in shut | +0.7 in over Max |
| Thickness | 8.75 mm | 5.2 mm open, 11.3 mm shut | Duo at both ends |
| Weight (Pro / Max) | 211 g / 249 g | 254 g | +5 g over Max |
| Frame | Aluminum unibody | Grade 5 titanium | Titanium on Duo |
| Rear cameras | Three 48MP, 8x tele | Two 48MP, 2x crop | No tele on Duo |
| Zoom range | 16x | 4x | 4x the reach on Pro |
| Sustained vs 17 Pro | Up to 40% | Up to 35% | +5 points on Pro |
| Video (Pro / Max) | 36 h / 45 h | 31 h open, 44 h shut | +1 h Max over shut |
| Biometrics | Face ID | Touch ID, side button | Duo drops Face ID |
For anyone who shoots past arm's length, the camera rows decide it. The Pro pair's Main camera, per Apple's iPhone 18 Pro release, moves its aperture from f/1.48 to f/4, and the 48MP Telephoto behind the tetraprism reaches 8x. The Duo has no telephoto lens at all. Its 2x comes out of the 48MP Fusion Main, and its answer is two tricks that need a second screen: Smart Take fires the shutter when you strike a pose in front of a standing Duo, and Duo Preview puts a live view on the outer display so the subject can fix their own framing. ProRes RAW, Apple Log 2, and Genlock stay on the Pro side, per AppleInsider, which also has the Duo's weight and thickness figures.
What both share
- A20 Pro with a 6-core CPU and 7-core GPU
- 256GB to 2TB storage and IP68
- ProMotion to 120Hz, Always On, 3,000 nits outdoor
- 50% in 30 minutes on MagSafe or Qi2
The accessory fine print matters more than the chip. iPhoners who keep a wallet on the back should know that Apple's compatibility list leaves the Duo off MagSafe wallets, according to AppleInsider, and the iPhone Duo MagSafe accessories video goes deeper on fit. Apple Pencil with USB-C support is promised for a later update, so the Duo ships without it. And the Duo is eSIM-only in every country, while the 18 Pro keeps a nano-SIM tray outside the 12 markets Apple lists as eSIM-only.
Anyone coming from a 17 Pro has the iPhone 18 Pro vs 17 Pro comparison for the generational side. My rule for first-gen Apple hardware still holds here: it's for early adopters, and the Duo's hinge has more than 100 parts that nobody has lived with yet. The iPhone 18 Pro ships September 18. The Duo opens pre-orders October 16 and ships a week later, which leaves four weeks to hold an 18 Pro in a store before committing to the fold.
