Apple has an online tool that helps you check your trade in value. The process is easy and requires you to answer a few questions about your device. First, you'll need to provide the device's serial number, model, and condition. You'll also need to answer a few questions about the device's features and recent repairs. Once you've provided the necessary information, Apple will provide an estimated trade-in value for your device. If you agree with the estimated value, you can follow the directions provided to complete the trade-in process.