At some point in the first half of 2025, Samsung is expected to debut the Galaxy S25 Slim, a thinner Galaxy phone similar to the much-rumored iPhone 17 Air.

But until now, we have seen no reports of how thin the device might actually be; thanks to Samsung's regular leaker Ice Universe, we now have at least a range.

The tipster posted on Weibo that the Galaxy S25 Slim “may be 6.x mm thick” (machine translation). The exact thickness is not known, but it will be between 6 mm and 6.9 mm.

For reference, the thinnest non-folding Galaxy phone today is the Galaxy S24, which is 7.6 mm thick, the same as the S23 and S23 Plus. Even at a maximum of 6.9 mm, the S25 Slim is remarkably thinner than any current Galaxy device.

Allegedly, Apple wants the iPhone 17 Air to be less than 6mm. That would make it significantly thinner than the 7.8 mm iPhone 16.

However, the Galaxy S25 Slim would not be Samsung's slimmest foldable phone; in 2015, the company announced in China that it would be 5.8 mm deep, slimmer than other phones of the time, including the 6.3 mm A7 and 6.7 mm Galaxy Alpha The company launched the stunning mid-range Galaxy A8 (h/t Digital Trends); the global version launched in 2018 somehow added 3 mm to the device, making it 8.4 mm thick.

Adding the foldable device makes the Honor Magic V3 the thinnest phone in the world, revealing a different thinness story. The handset measures 9.2 mm when closed, but only 4.4 mm when open.

The Samsung Galaxy Z Fold 6, on the other hand, is 12.1 mm large when closed, but less than half that at 5.6 mm when open.

The Galaxy S25 Slim is not expected to debut along with the S25 Ultra in January. Instead, rumors point to a spring, possibly April, launch.