The iPhone 18 Pro weighs 211 g and the iPhone Duo weighs 254 g, a difference of 43 g, according to Apple’s tech specs. Closed, the Duo is 84.1 mm wide, 117.8 mm tall and 11.3 mm thick, against 71.9 x 150.0 x 8.75 mm for the iPhone 18 Pro. It is shorter and wider than the Pro, and about 2.5 mm thicker.
The more surprising comparison is with the iPhone 18 Pro Max. At 249 g and 78.0 x 163.4 x 8.75 mm, the Pro Max is only 5 g lighter than the Duo and considerably taller. Apple’s numbers below show where the foldable’s bulk actually goes, and what that means for a pocket. For the price side of the decision, see our iPhone Duo vs iPhone 18 Pro Max comparison.
iPhone 18 Pro vs iPhone Duo size and weight
| Measurement | iPhone 18 Pro | iPhone 18 Pro Max | iPhone Duo (closed) | iPhone Duo (open) |
|---|---|---|---|---|
| Width | 71.9 mm | 78.0 mm | 84.1 mm | 164.6 mm |
| Height | 150.0 mm | 163.4 mm | 117.8 mm | 117.8 mm |
| Depth | 8.75 mm | 8.75 mm | 11.3 mm | 5.2 mm |
| Weight | 211 g (7.44 oz) | 249 g (8.78 oz) | 254 g (8.96 oz) | 254 g (8.96 oz) |
| Display | 6.3 inches | 6.9 inches | 5.4 inches | 7.6 inches |
| Frame | Aluminum unibody | Aluminum unibody | Grade 5 titanium | Grade 5 titanium |
All dimensions and weights are from Apple’s tech specs pages for the iPhone 18 Pro and iPhone Duo.
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211 g vs 254 g: the weight gap in context
The Duo is 43 g heavier than the iPhone 18 Pro, roughly a 20 percent increase. Against the Pro Max the gap is 5 g, which is about 2 percent and unlikely to register in the hand. In other words, the Duo weighs like a Pro Max, not like something in a class of its own.
Apple builds the Duo’s frame and hinge cover from Grade 5 titanium, and it says the hinge alone has more than 100 components. The Pro models use an aluminum unibody. Apple has not published the weight of the hinge or of either accessory case.
Closed: shorter and wider than any iPhone 18 Pro
Folded, the Duo is 117.8 mm tall, which is 32.2 mm shorter than the iPhone 18 Pro and 45.6 mm shorter than the Pro Max. It is 12.2 mm wider than the Pro and 6.1 mm wider than the Pro Max. The shape is closer to a passport than to a slab phone, which is the format Apple describes for the open device.
The trade is thickness. At 11.3 mm closed, the Duo is 2.55 mm thicker than either Pro, which are 8.75 mm. In a front pocket it sits lower and fatter; in a back pocket it does not poke above the seam the way a 163.4 mm Pro Max can. That 5.4-inch outer display has more than 90 percent of the 18 Pro’s screen area, so the closed phone is usable without opening it.
Open: wider than a Pro Max is tall, at 5.2 mm
Unfolded, the Duo measures 164.6 mm across, which is 1.2 mm more than the Pro Max’s height, and 117.8 mm tall. Apple lists it at 5.2 mm thick open, well under the 8.75 mm of the Pro models. The 7.6-inch inner display is, by Apple’s measure, 50 percent larger than the Pro Max screen.
An open Duo does not go into a pocket; it is a small tablet at that point. The design assumes you fold it before you move, and Apple says iOS 27 responds to the phone’s pose, with StandBy, landscape, portrait, seated and standing positions.
What folds into a pocket, in numbers
- Shortest in the pocket: iPhone Duo closed, 117.8 mm, against 150.0 mm for the 18 Pro and 163.4 mm for the Pro Max.
- Thinnest in the pocket: iPhone 18 Pro or Pro Max, 8.75 mm, against 11.3 mm for the closed Duo.
- Narrowest: iPhone 18 Pro, 71.9 mm, then the Pro Max at 78.0 mm, then the Duo at 84.1 mm.
- Lightest: iPhone 18 Pro at 211 g, then the Pro Max at 249 g, then the Duo at 254 g.
The iPhone 18 Pro and Pro Max ship September 18 from $1,199 and $1,299. The iPhone Duo opens pre-orders October 16 and arrives October 23 from $1,999. The remaining specs are in our iPhone 18 Pro official guide and our iPhone Duo specs roundup.
