Innie or outie? How to define the first generation of foldable phones

Does the screen fold up on the inside, or does it wrap up on the outside? Let's get the taxonomy down.

MWC 2019 has brought the first production foldable phones to market, and there's been a distinct difference in the approaches of the major reveals. The Samsung Galaxy Fold opens up like a book to reveal the flexible OLED display inside. The Huawei Mate X does the opposite — it folds away from you, wrapping the screen around the outside of the device.

They're both impressive technical accomplishments, even if these first generation devices are going to be saddled with unforeseen compromises and eye-watering price tags. But... what do we call these things? They're foldables, yes, but what kind of foldable? We've got names for various types of laptops (2-in-1, clamshell, convertible) and used to have different classifications for phones (flip, slider, candy bar, slate, etc).

For now there are two kinds of foldables: innies and outies.

The innie

The Samsung Galaxy Fold is the quintessential innie foldable phone. Pull apart its two halves and the 7.3-inch screen unfolds before you. The big screen is on the inside, ergo, it's an innie.

There are advantages and disadvantages to this design approach. On the plus side, it protects the expected-to-be-fragile flexible plastic display cover from potential damage when folded. It lets you have a more compact footprint to the device, and on the aesthetics front it allows the manufacturer a chance to design something that's more than just a screen. The durability of these folding screens is an open question for consumers, but the innie foldable may have the advantage of unfolding and pulling the screen taut to diminish any wrinkling of the plastics.

There's added screen protection and durability, but the phone can't fold flat.

But there are some cons, too. The phone can't fold flat, as that would immediately crease the display, so there has to be at least some hinge gap in the closed device. Because all that screen disappears on the inside, there has to be a second display on one of the outside panels to use while closed (Samsung calls this the cover screen, as in a book cover). And the camera situation gets awkward, as there are the main rear shooters, a front-facing camera for the cover, and a front-facing camera (or two) for the inside — and those inside cameras need to go somewhere, so there's a substantial offset notch. The alternative would be to place the front-facing cameras in a lip that sticks up over the edge so they're visible when both closed and open.

In the future some of these downsides could be obviated — screens that can fold more crisply without damage (ala Westworld), cameras embedded in the displays, and other technological advances will fix some of these issues.

The outie

On the flip side, there's the Huawei Mate X. This foldable screen is the stuff of sci-fi, wrapping around the outer radius of the hinge and folding away from you. It is the very definition of the outie.

The outie has some distinct advantages over the innie.

The outie has some distinct advantages over the innie. Only the one display panel is required, since by virtue of the design you already have screen around the entire outside of the phone. The outie design reduces the number of required cameras, since there is already a camera facing facing one half of the folding screen — four of them on the Mate X, actually. Since the screen is on the outside, it avoids creasing by wrapping around the internal components — thus the device can fold flat back-to-back and be thinner overall. Also, it just looks so damn cool.

All those advantages come with some disadvantages, though. The folding mechanism has to be somewhat complicated and incredibly precise, ensuring that the folding action brings the opened display fully taut but still rounded smoothly when closed. The camera situation requires that either there be a margin on one side of the device, or that the fold not be centered (the latter being Huawei's approach). The biggest pain point will be the fact that the screen is always facing out, exposed on all sides to danger. There's no way that the flexible plastic display covering they use will hold up nicely to the kind of abuse we heap upon traditional phones — particularly on the "back" of the phone when it's folded.

Which is better?

The innie foldable and the outie foldable each have significant pros and notable cons. Truth is, at least for this first generation, there is not one form that is better than the other. There are so many questions, mainly surrounding durability, that it will take years (mostly for improved materials and engineering) before we can have a final verdict. And with how much these insane things cost, it will be years before they're remotely affordable for the average phone shopper anyway — and this is in a world where flagship phones have hit the $1000 mark and stayed there.

So which do you prefer, the innie or the outie?