The short answer is: quite.
YouTuber JerryRigEverything puts Samsung’s new flagship smartphone through a battery of torture tests including scratching the front and back glass, holding a lighter to the screen, and attempting to bend the phone in half.
The tempered glass screen survives any deep scratches up to a 7 on the Mohs Hardness Scale—which correlates roughly to quartz—meaning the keys or loose change in your pocket probably won’t do much damage. Flames seem to not be very effective at slowing down the Edge either, thanks to a solid aluminum body and internal liquid cooling. And although repeated bending might break the waterproof seal, it probably won’t permanently kink, which is all we can really ask for until they start making phones that can bend intentionally.