One of the questions I heard people asking about the newly-announced iPhone X is if they could use it in sunlight. The short answer is: no (or at least not any better than you can currently use an iPhone 6 or 7).

The iPhone X’s listed maximum screen brightness is 625 nits (that is, 625 candelas/square meter); Apple advertised the same brightness for the iPhone 7. The Apple Watch 2 and later advertise a maximum brightness of 1000 nits. According to this page if you’re in full sunlight under a bright sky, you’d want your display to have a brightness of 800-1000 nits in order to be readable (that level of sunlight itself has an ambient brightness of 7000 – 10,000 nits). So the Apple Watch is usable in sunlight, but iPhones – including the iPhone X – would need to be 30-70% brighter to do the same.