Cubic Millimeters to US Gallons (mm³ to gal)

1 cubic millimeter equals 2.641720524×10⁻⁷ US gallons (rounded).

1 cubic millimeter = 2.641720524×10⁻⁷ US gallons

How to convert cubic millimeters to US gallons

To convert cubic millimeters to US gallons, multiply the number of cubic millimeters by 2.641720524×10⁻⁷. The factor is rounded to 10 significant digits. To go the other way, multiply US gallons by 3,785,411.784.

US gallons = cubic millimeters × 2.641720524×10⁻⁷

Example: 10 cubic millimeters = 0.000002641720524 US gallons.

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

Cubic Millimeter (mm³)

Metric (SI)Current unit

One thousandth of a milliliter. Used for tiny volumes.

Geometry supplies the name: a cubic millimeter is the volume of a cube whose edges are each one millimeter long, equal to 10 to the minus 9 cubic meters. Because 1,000 of them fill one cubic centimeter, it is one thousandth of a milliliter, and it is the smallest volume that is commonly written as a cube of length rather than with a liter prefix.

Its tidy equality with the microliter rests on a decision taken in 1964, when the 12th General Conference on Weights and Measures went back to the original definition of the liter as exactly one cubic decimeter. From 1901 until then the liter had been tied to the space taken by a kilogram of water, which made it about 1.000028 cubic decimeters, so volumes in cubic millimeters and microliters differed very slightly. Today 1 mm3 equals 1 microliter exactly, and the figure used here, 0.000001 liter, follows directly from that.

1 cubic millimeter = 0.000001 liters (exactly).

Sources: Wikipedia: Cubic metre; Wikipedia: Litre

US Gallon (gal)

US customaryCurrent unit

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

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