The "g=grams" and "g=gallons" confused me at first. Nobody wants to type out "grams" and "gallons". The experience folks here (and the labels!) use an assumed short-hand based on context that confuses us newbies. But you get the hang of it quickly.
I have a dedicated "weighing cup" just for Celsius. It's actually a small plastic cap from a Calibri butane refill canister
for my cigar lighters. I weighed my cup, wrote down the grams, and always subtract that from my final weight. I also use "grams per one gallon sprayed over 1000 square feet" for my units.
For my first-time-ever spray, I did the "middle" application rate just in case I screwed up either way. But I nailed it and got rid of most of my weeds without fading my Bermuda at all. So I used the "high" rate when I went back to spot spray some stubborn Virginia Buttonweed here and there. Surprisingly, the high rate also did not fade or brown my Bermuda. But it sure killed the buttonweed!