Congii to US Gallons (congius to gal)
1 congius equals 0.8651634715 US gallons (rounded).
How to convert congii to US gallons
To convert congii to US gallons, multiply the number of congii by 0.8651634715. The factor is rounded to 10 significant digits. To go the other way, multiply US gallons by 1.155850926 (rounded).
US gallons = congii × 0.8651634715
Example: 10 congii = 8.651634715 US gallons.
Pints, quarts, gallons and fluid ounces differ between the US and the UK. Units are labeled 'US' or 'imperial' to avoid confusion.
Approximate value. Standards for the congius varied by place and period, so this converter uses the most commonly cited value. Treat results as estimates, not exact figures.
About these units
Congius (congius)
Six sextarii, about 3.27 L. A Roman liquid measure a little under a US gallon.
Eight congii made up one amphora quadrantal, and each congius was defined as a cube measuring half a Roman foot on each side. Wikipedia's table gives it as 3.27 L, which is the figure used here. The cube definition links it directly to the length standard, so any doubt about the exact length of the pes carries straight into the volume.
Inside the liquid scale, the congius was divided into 6 sextarii, and further down into 72 cyathi. Larger vessels such as the culeus were counted in congii, with 160 of them to the culeus. Because it came to roughly 3.3 L, it sits near the modern US gallon of 3.785 L, though it is noticeably smaller. Surviving vessels never match each other exactly, and the sextarii they imply range between 500 and 580 mL, so a congius from archaeology could fall anywhere from about 3.0 to 3.5 L.
1 congius = 3.275 liters (approximately).
Sources: Wikipedia: Ancient Roman units of measurement
US Gallon (gal)
Exactly 231 cubic inches or 3.785411784 liters (128 US fluid ounces). About 17% smaller than the imperial gallon.
The US gallon is a survivor of English wine trade. Around 1706, a statute in Queen Anne's reign fixed the wine gallon at exactly 231 cubic inches, settling confusion among the competing gallons for wine, ale and corn. British colonies in North America used that wine gallon, and in 1824 Britain replaced all its gallons with a new imperial one while the United States kept the old measure. It was adopted as the legal US standard in 1836 and is still defined as exactly 231 cubic inches, or 3.785411784 liters.
That makes the US gallon about 17 percent smaller than the imperial gallon, a difference that explains why American and British fuel-economy figures cannot be compared directly. Everyday uses are milk jugs, paint cans and gasoline pumps. One gallon divides evenly into four quarts, eight pints, sixteen cups and 128 fluid ounces. A gallon of water weighs a little over 8 pounds, an easy figure to remember when loading a car with water jugs.
1 US gallon = 3.785411784 liters (exactly).
Sources: Wikipedia: Gallon; NIST SP 811, Appendix B.8: conversion factors for volume
Related conversions
- US gallons to congii (reverse)
- Congii to liters
- Congii to milliliters
- Congii to US cups
- Congii to US fluid ounces
- Liters to US gallons
- Milliliters to US gallons
- US cups to US gallons
- US fluid ounces to US gallons
- Cubic meters to US gallons
- Cubic centimeters to US gallons
- US quarts to US gallons
- US pints to US gallons
- US tablespoons to US gallons
- US teaspoons to US gallons
- Metric cups to US gallons
- Metric tablespoons to US gallons
See all volume units.