TotalTimeTracker
Unfortunately after 2017 changes in Google Calendar this kind of widget no longer works :-(
Gadget for Google Calendar to display the total time of the tasks/events showed (By day and/or by view).
To load one of the gadgets in your Google Calendar you have to load the raw xml url as a parameter after: https://www.google.com/calendar/render?gadgeturl=
So these links should work: