My wife recently asked the question, “if I just wanted salt instead of soy sauce in the recent ‘Steamed’ Clams With Ginger And Garlic, how much salt would you have to use?”. It seemed to me that was more of a question of salinity. Looking up some information on the web suggested 1/4 t of salt was about 581 mg of sodium.
I then decided to grab a bottle of Kikkoman Organic Soy Sauce. Its nutrition label said that 1 T of soy sauce had 1020 mg of sodium. Half that amount of that soy sauce (i.e. 1/2 T [aka 1 t + 1/2 t]) supposedly would have 510 mg of salt. Since different formulations of soy sauce tends to vary in their amount of sodium/salt, I decided it might be ‘safe’ to use the 1/2 T rule when I needed to use a comparable amount of soy sauce to reach a desired salinity in a dish.