(Image credit: MacRumors)

When you’re about to launch your first-ever foldable device, you know it needs to leave a lasting impression. That’s why design is paramount to making the iPhone Ultra compelling — a device already tipped to be the thinnest iPhone ever.Apple’s entry into the foldable market isn't just another product launch because it’s a defining moment that will set the hardware benchmark for what an ultra-premium, notebook-style foldable should be. While Apple has the chance to set a new standard with its record-breaking thin chassis, it faces fierce competition from rivals like Samsung, Motorola, and Google, who have spent years iterating their designs.Here’s what the rumors and leaks say about how thin Apple could make the iPhone Ultra.It’s going to be thinner than the iPhone Air

(Image credit: Tom's Guide)There’s very little doubt by now that the iPhone Ultra is going to be a solid contender for best foldable phone when it’s released. In fact, one of the biggest reasons for that comes from a longstanding rumor that it will be the thinnest iPhone ever at 4.5 mm unfolded — something reliable leaker Ming-Chi Kuo has claimed for more than a year now.At under 5 mm, it would easily undercut the ultra-slim iPhone Air’s impressive 5.64mm chassis and blow past traditional slates like the standard iPhone 17. What’s even more impressive is how the Ultra still retains a thin construction when closed, with rumors suggesting it would sit around 9mm to 9.5mm thick — only marginally thicker than the current iPhone 17 Pro and 17 Pro Max.Comparing the folded and unfolded states to Apple’s current lineup highlights just how dramatic this level of engineering is: