Convert millilitres to gallons

One thousand millilitres is 0.264172 of a US gallon. Divide the value in millilitres by 3,785.411784: gallons = millilitres ÷ 3,785.411784[1].

The answers come out small, because a single gallon holds nearly four thousand millilitres. A 500 ml bottle gives 0.132086 of a gallon. A standard 750 ml wine bottle is 0.198129, just under a fifth. A two-litre bottle works out at 0.528344, so it takes two of them to pass a full gallon. Below 3,785.41 millilitres every result is a fraction, with up to six decimal places.

Which gallon you are converting to decides the result. On the imperial setting a thousand millilitres gives 0.219969 of a gallon, because an imperial gallon holds 4,546.09 millilitres[2]. On the US dry setting it gives 0.227021, and that gallon holds 4,404.88 millilitres[3]. The Gallon type switch under the fields sets the measure.

For the other direction use the gallons to millilitres converter, and above a few litres the litres to gallons converter is the easier read.

The prefix milli- means a thousandth, so a millilitre is a thousandth of a litre. It takes up exactly one cubic centimetre, which makes 10 millilitres and 10 cubic centimetres the same volume[4].

In the US table of liquid volume the gallon sits at the top, and the smaller units come from dividing it. A gallon splits into 4 quarts, 8 pints and 128 fluid ounces, and each of those divisions has its own figure in millilitres[5]. A quart is 946.35 millilitres. A pint is 473.18 millilitres. A fluid ounce is 29.57 millilitres, and the ounces to millilitres converter handles that last step on its own.

The imperial series divides the gallon into the same four quarts and eight pints, but fits 160 imperial ounces inside it, so its ounce measures 28.41 millilitres[2]. The same unit name covers a different volume in each system, which is why the country a label comes from matters.

The 750 millilitre bottle took the place of an older American size based on the gallon. In the United States wine and distilled spirits were sold in bottles called fifths, a fifth of a US gallon: 25.6 fluid ounces, which works out at 757.08 millilitres. For distilled spirits it was the usual bottle size until 1980[8].

In 1975 the Bureau of Alcohol, Tobacco and Firearms proposed metric bottle sizes to take effect in January 1979, with a one-year changeover period[8]. The 750 millilitre bottle that replaced the fifth, sometimes called a metric fifth, is 7.08 millilitres smaller, just under 1 per cent, and it is now the usual size of a wine bottle[8].

The arithmetic runs the other way too. Six 750 millilitre bottles make 4,500 millilitres, which is 714.59 millilitres more than a US gallon and 46.09 millilitres less than an imperial gallon.

A bottle of 473 millilitres and one of 568 millilitres both hold a pint, measured in two different systems. The US pint is an eighth of a US gallon: divide the gallon by eight and you get 473.18 millilitres[5].

The imperial pint is an eighth of an imperial gallon, and British weights-and-measures law gives its capacity directly: 0.56826125 of a cubic decimetre[2]. The two pints share a name and differ by 95.08 millilitres.

The US alcohol tax bureau keeps both values on its list of permitted wine bottle capacities, next to the metric 500 and 1,000 millilitres[6]. That is why a single shelf in the States can carry 473, 500 and 568 millilitre wine bottles side by side, each one the product of a different system.