The amount is correct, but I usually give it 1-3 days in a row in addition to their medicated water. It's quite safe, so don't worry about giving both too much.
Weight of bird in pounds, divide by 2.2, times 20, divide by 96 = the number of ml to give.water. Is there a reason that you don't want to put in their water?
Well as much as I can get her to hold still on the scale, she's between 3 lb, 5oz and 4 lb. as far as her water, I guess I can, but she's in my guest bath, and her water bowl is only about a cup of water. The math you gave, is that to be added to the water? Even if it's only a cup? Or is that diluting the Corid to give orally? I'm confused
So 4 / 2.2 x 20 / 96 = 0.38 mL of something 😊