US Cups to Acre-feet (cup to ac⋅ft)
1 US cup equals 1.918052048×10⁻⁷ acre-feet (rounded).
How to convert US cups to acre-feet
To convert US cups to acre-feet, multiply the number of US cups by 1.918052048×10⁻⁷. The factor is rounded to 10 significant digits. To go the other way, multiply acre-feet by 5,213,622.857 (rounded).
acre-feet = US cups × 1.918052048×10⁻⁷
Example: 10 US cups = 0.000001918052048 acre-feet.
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)
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
Acre-foot (ac⋅ft)
The volume of water that covers one acre to a depth of one foot: 43,560 cubic feet or about 1,233.48 cubic meters. Used for reservoirs and irrigation in the US.
Water engineers in the western United States took the acre, a land measure of 43,560 square feet that began as a strip one chain by one furlong, and gave it a depth of one foot to describe water. The result, the acre-foot, covers 43,560 cubic feet, which is about 1,233.48 cubic meters or roughly 1.23 million liters. In US gallons it comes to about 325,851.
The unit is used for reservoirs, canals, aqueducts, irrigation allotments and river flows, where the volumes are too large for gallons to be comfortable. A common planning rule treats one acre-foot per year as the water use of a suburban household, although Santa Fe households average closer to a quarter of that.
The size depends slightly on which foot is used. The figure used here follows the international foot of exactly 0.3048 m. The older US survey foot makes the unit about 0.0006 percent larger, a gap that matters little in practice. Most other countries state such volumes in cubic meters, megaliters or cubic kilometers.
1 acre-foot = 1,233,481.838 liters (approximately).
Sources: Wikipedia: Acre-foot; Wikipedia: Acre
Related conversions
- Acre-feet to US cups (reverse)
- US cups to liters
- US cups to milliliters
- US cups to US gallons
- US cups to US fluid ounces
- US cups to cubic meters
- US cups to cubic centimeters
- US cups to US quarts
- US cups to US pints
- US cups to US tablespoons
- US cups to US teaspoons
- US cups to metric cups
- US cups to metric tablespoons
- Liters to acre-feet
- Milliliters to acre-feet
- US gallons to acre-feet
- US fluid ounces to acre-feet
See all volume units.