How can I calculate with time?
I would like to substract a date/time helper from the current time. afterwards I would like to use the endresult in a “delay”.
You can use the timestamp. If you fx. have a date/time helper called start_time, you can use the following
{{ now().timestamp() - state_attr('input_datetime.start_time','timestamp') }}
which will give you seconds passed since the start time.
Thx, this worked for me 