Estimated trade-in values are based on your device's current market value and are subject to change. It may include additional promotional value based on Google Store promotions.
The estimated trade-in value is based on the information that you provide about the model and condition of your trade-in device on the configuration page during the checkout process. The final trade-in value is based on inspection of your old device after it's received. Any differences between the information that you provide and your device's actual condition may impact the device's final trade-in value.
Additional details can be found in the trade-in Terms and Conditions.