Question: what iphone is compatible with apple watch series 3?
Answer: 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). If you buy a new version of either model, you'll need an iPhone 6s or later, running iOS 13 or later.