As with all iPhones, Apple takes the cheap way out and gives you a 1A brick and 3’ cable. The X will charge just fine overnight with that. For faster charging you can use the methods mentioned above in previous posts, i.e. iPad charger or other 2.1A chargers work great. The fastest way to charge the X will be to use a quality charger and cable that meet the USB PD (power delivery) spec. Not sure how much power it can take as they aren’t out in the wild yet, and Apple isn’t very forthcoming with the full capabilities. Probably because they don’t want to bring attention to the fact that they’re slinging $1150 phones that need $80 worth of chargers and cables to charge at max speeds.