Substitute Hon Dashi for Bonito I understand that the ingredients are not even nearly the same
If making a bonito dashi, grams-for-grams, how much Hon Dashi granules to substitute for bonito flakes?
This could partly be worked out from dashi packet or powder package recipes, but the powders and packets are not just dried bonito flake extracts
I do understand all answers will be approximations, and approximations are appreciated
thanks!
Hondashi isn't really a substitute for the bonito flakes. It is a concentrate to make dashi...sort of like a bullion cube.  It is made of msg, salt, sugar, yeast, and dried bonito.  In general, one would use about a teaspoon to a cup of water to make dashi.  If you are beginning with prepared dashi, and looking for more umami, I might just add a bit at a time (1/4 tsp) and taste until you are satisfied.  Alternately, you don't need bonito to make dashi.  It can be as simple as kombu and water.  So, this might, in part, depend on your use.