Want real-time metrics of your data usage? Look no further than your device.
iOS
iOS provides statistics on your cumulative data usage. In order to track how much data you used in a specific time period, you must reset your statistics.
Go to Settings > Cellular scroll down to the very bottom and tap Reset Statistics.
Once reset, you'll be able to see how much data you have used from the date of your reset by going to Settings > Cellular > Mobile Data.
Android
Google Pixel
To view daily data usage on your Android device, go to Settings > Network & Internet.
Select SIMs.
Tap App data usage to check your data consumption from your current period. You can tap within the data usage graph to view daily usage.
Samsung and other Android devices.
To view daily data usage on your Android device, go to Settings > Connections.
Select Data usage.
Tap Mobile data usage to check your data consumption from your current period. You can tap within the data usage graph to view daily usage.