The new foldable iPhone Duo is the "thinnest iPhone ever," according to Apple. When unfolded, the device is 5.2mm thick, making it 0.4mm thinner than the 5.6mm iPhone Air. Rumors suggested it could be as thin as 4.5mm when unfolded, similar to Samsung's Galaxy Z Fold8, but it didn't end up that thin. At 5.2mm, it's just a little bit thicker than the 5.1mm 13-inch iPad Pro, which is Apple's thinnest device. iPhone 17 Pro Max and iPhone 18 Pro Max are both 8.75mm thick. The iPhone Duo is also Apple's heaviest iPhone to date at 254 grams, which is five grams heavier than the 249-gram ‌iPhone 18 Pro‌ Max. It has a 7.6-inch inner display when it's open and a 5.4-inch outer display when it's closed, and it has a short, wide design. Related Roundups: iPhone Air, iPhone Fold Tag: September 2026 Apple Event Buyer's Guide: iPhone Air (Neutral) This article, "iPhone Duo Beats iPhone Air as Apple's Thinnest iPhone, But Only When Open" first appeared on MacRumors.com Discuss this article in our forums

The new foldable iPhone Duo is the "thinnest iPhone ever," according to Apple. When unfolded, the device is 5.2mm thick, making it 0.4mm thinner than the 5.6mm iPhone Air. Rumors suggested it could be as thin as 4.5mm when unfolded, similar to Samsung's Galaxy Z Fold8, but it didn't end up that thin. At 5.2mm, it's just a little bit thicker than the 5.1mm 13-inch iPad Pro, which is Apple's thinnest device. When folded, the iPhone Duo is 11.3mm thick. For comparison, the iPhone 17 Pro Max and iPhone 18 Pro Max are both 8.75mm thick. The iPhone Duo is also Apple's heaviest iPhone to date at 254 grams, which is five grams heavier than the 249-gram iPhone 18 Pro Max. It has a 7.6-inch inner display when it's open and a 5.4-inch outer display when it's closed, and it has a short, wide design. Pre-orders for the iPhone Duo begin on October 16 ahead of an October 23 launch date.Related Roundups: iPhone Air, iPhone Fold Tag: September 2026 Apple Event Buyer's Guide: iPhone Air (Neutral) This article, "iPhone Duo Beats iPhone Air as Apple's Thinnest iPhone, But Only When Open" first appeared on MacRumors.com Discuss this article in our forums