From the Hicks:

In a metric system, one milliliter of water takes up one cubic centimeter, weighs one gram, and requires the cost of one calorie of energy to heat up by one degree — which would be 1 percent of its freezing point to boiling point. The mass of hydrogen is equal to the mass of one mol of atoms in it.

While in the Imperial System the answer to the question, “How much energy will it take to boil a gallon of room temperature water?” will be “Go in %:No!” because you can’t directly match any of these values.