Question: is apple watch series 1 compatible with iphone 5s?
Answer: Apple Watch First Generation is compatible with the iPhone 5 or later, running iOS 8.2 or later. Apple Watch Series 1 and Series 2 are compatible with the iPhone 5 or later, running iOS 10 or later. Apple Watch Series 3 has two models, one with a cellular plan like your phone (LTE) and one without (Non-LTE).