You ought to know the difference between an english or metric drop, Alchemy... (for the rest of us: there isn't any).
This is a figure I calculated based on data available from a machinist handbook, 26th ed (for those who have it), and actually, it's for a full gallon of water, not a typical 1/2 gallon (usually less), and the temp difference is 20 deg C, which is far higher than most of us encounter.
Do you want me to dig up the post?
