When it comes to kitchen recipes, there are quite a few differing definitions when it comes to the size of the teaspoon. In the US the teaspoon was traditionally defined as 1/6 of a fluid ounce, or a little more than 4.9 milliliters, and in England it's usually regarded as 1/8 of an imperial fluid ounce, or 3.5 milliliters.

But did you know that the United States Food and Drug Administration requires that for nutrition labeling 1 teaspoon = 5 milliliters? And that 1 tablespoon = 15 milliliters? By the way, this calculator uses the USFDA definition of the teaspoon.

Weight measures have suffered from a similar lack of international consensus. Although the avoirdupois ounce has been mostly agreed upon in the kitchen for the last 50 years, the mass of precious metals is still measured by the troy ounce, which is nearly 10% heavier. So the answer to the question "Which weighs more, an ounce of sugar or an ounce of gold?" is quite clear: gold!