How do I know if my Wi-Fi is 2.4 or 5?

From your smartphone’s Wireless settings page, look at the names of your Wi-Fi networks.

1. A 2.4 GHz network may have "24G," "2.4," or "24" appended to the end of the network name. For example: "Myhomenetwork2.4"
2. A 5 GHz network may have "5G" or "5" appended to the end of the network name, for example "Myhomenetwork5"