Listening to a 128 Kbit/s stream uses approximately 60 MB per hour. Lower bit rate streams (e.g., 64 or 32 Kbit/s) use up less, while larger streams (> 128 Kbit/s) use up more data. Please be sure to tap 'Pause' and stop streaming when you've finished listening.
More and more stations switch to an adaptive streaming format, which adapts the quality and bitrate streamed to the internet connection of the user. So in these cases, the data used depends on the internet connection as well, – and ensures that the lowest possible data is used. Our iOS and Android apps already support adaptive streaming.