US Cups to Firkins (cup to firkin)

1 US cup equals 0.005782459615 firkins (rounded).

1 US cup = 0.005782459615 firkins

How to convert US cups to firkins

To convert US cups to firkins, multiply the number of US cups by 0.005782459615. The factor is rounded to 10 significant digits. To go the other way, multiply firkins by 172.9367893 (rounded).

firkins = US cups × 0.005782459615

Example: 10 US cups = 0.05782459615 firkins.

Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.

About these units

US Cup (cup)

US customaryCurrent unit

One sixteenth of a US gallon, 236.588 mL (8 US fluid ounces). The standard US recipe cup.

Cups began as household drinking vessels, not scientific units, which is why they remain the messiest measures in the kitchen. The US customary cup was defined by slicing up the gallon: half a pint, or eight US fluid ounces, about 236.6 milliliters. Unlike the larger units, nobody ever fixed it to a physical vessel, so it exists only as a fraction of the gallon.

The customary cup is not the only American cup. For nutrition labels, US regulation defines a cup as exactly 240 milliliters, a rounder figure that sits slightly above the customary size. Packaged foods therefore list a serving in the legal cup while a measuring cup from the hardware store follows the customary definition. The gap is 3.4 milliliters, which hardly matters for soup but can matter in baking. Cup measures also hide the weight of dry ingredients, since a cup of sifted flour and a cup of packed flour differ substantially, which is why much of the world prefers grams.

1 US cup = 0.2365882365 liters (exactly).

Sources: Wikipedia: Cup (unit); NIST SP 811, Appendix B.8: conversion factors for volume; 21 CFR 101.9: nutrition labeling household measures

Firkin (firkin)

Imperial (British)Traditional unit (still used in some regions)

9 imperial gallons (40.9 L), a quarter of a barrel. A traditional cask size for beer.

Probably from Middle English ferdekyn, which in turn likely comes from a Middle Dutch diminutive of vierde, fourth, the firkin is literally a little quarter: a quarter of a barrel. For beer in Britain that means 9 imperial gallons, about 41 liters (40.9 L here), or 72 imperial pints.

The word has been used for other goods too. A wine firkin was much bigger, at 70 imperial gallons by one reckoning, while British butter and cheese were sold by the firkin of 56 pounds, about 25 kilograms. An American dry firkin of 9 US gallons is only about 34 liters, and the word could also mean any small wooden tub for butter, lard or fish. Authors such as William Robinson in 1825 treated it as a recognised trade measure.

1 firkin = 40.91481 liters (exactly).

Sources: Wikipedia: Firkin (unit); Wikipedia: Barrel (unit); Wikipedia: Cask ale

Related conversions

See all volume units.