I have only 3 GB of internet traffic per mounth, so I should know what is the quantity of data downloaded by Spotify app, per second or minute, during the use (listening of song).
Hey! Welcome to the community :)
The streaming rates of all of Spotify's qualities are outlined in this help page from which you can work out your data usage for streaming.
Note, that the application will use more data than just streaming, since it will use data to load playlists, searches and cover art.
PeterSpotify Community Mentor and TroubleshooterSpotify Last.FM Twitter LinkedIn Meet Peter Rock Star Jam 2014
If this post was helpful, please add kudos below!