Data usage monitoring

[Raprap7]

Is there a way for me to keep track of my data usage? I have a limited 100GB monthly and would like to keep track on the usage. 

I have a laptop and a phone connected to the router, can I monitor the usage of both of them? 

In case of the laptop, is there a way to track the usage of each app or google chrome tab opened or games? I'm particularly interested if there's a way to know how much data it would cost me to watch a particular youtube video. 

Thanks! 

[Origami Cactus]

You can monitor the data usage from the router's software directly, and if you have an android phone you can monitor in the settings.

If you have a windows 10 laptop then you can measure the data usage in the data usage panel in settings, there you can also set a data limit. Also click the "view usage per app" button to see usage per app.

In youtube 480p is the sweet spot for data, as it uses about 2x less data than 720p, but is still somewhat watchable. You can see the youtube video size by using a video downloader.