the.com/fluid ounce
A volume that picked a fight with weight and confused everyone for centuries.
means A unit of liquid volume — roughly 30 milliliters in the US and about 28 in the UK — used to measure how much liquid fills a space, not how heavy it is.
from "Ounce" comes from the Latin uncia, meaning a twelfth part — originally a twelfth of the Roman pound or foot (the same root gives us "inch"). For centuries "ounce" measured weight, but liquids got their own version: the fluid ounce, defined as the volume occupied by an ounce of a particular liquid (in England, originally wine, later water). Because different liquids weigh different amounts, and because the US and UK fixed their gallons differently, the two nations ended up with fluid ounces of slightly different sizes — hence a volume that quarreled with weight and never quite reconciled.
- twin units
- US and UK fluid ounces are different sizes.
- volume not weight
- Measures space, despite sounding like the scale unit.
- odd ratio
- A US gallon holds exactly 128 fluid ounces.
- old roots
- Descends from the Roman uncia, meaning one-twelfth.
- the gap
- UK ounce is about 4 percent bigger.
us fluid ounce — 29.5735 milliliters, standard measurement in united states since 1836
imperial fluid ounce — 28.4131 milliliters, standard measurement in uk and commonwealth countries