Thanks Kim
Good to know my simplification works for imperial as well, thanks
SaltedFig -- Your method also works for American fluid ounces and ounces (by weight) because 1 fluid ounce of water = 1 ounce of water (by weight).
You're asking people to measure the volume of water rather than its weight. That's a good idea especially for people with smaller scales. Also you've simplified the math a bit in that 1.5/2 = 0.75. But otherwise we're both in agreement as to method. That's good.
Good to know my simplification works for imperial as well, thanks