File size in bytes using command prompt

How do I get the size of a file in bytes (purely in numbers) on Command prompt:

After much R&D I got to the following command:

FOR /F "usebackq delims==" %i in (`dir /b for.txt`) do %~zi


The last part after do can be replaced by SET %~zI = %size etc.. to use this in the batch files.
The delimitter is backq, i.e. ` and not '