: If buying from an open marketplace like Swappa, always ask for the battery maximum capacity percentage [30, 36].

For a "good piece"—meaning a reliable, high-quality device—the best place to buy an old iPhone is the store [8, 9, 32]. While it is typically the most expensive option, it is the only one that guarantees a brand-new battery , a new outer shell, and a genuine one-year Apple warranty [8, 34, 35].

: Offers "Amazon Renewed" devices backed by a 90-day to 1-year guarantee [8, 14, 17]. It's a popular choice for fast shipping and easy returns if the device doesn't meet your "good piece" standard [33, 41].