Quarts to Gallons Converter

US quarts to US gallons — quick reference

The formula, worked line by line

The conversion divides by four, and the four is a definition shared by both gallon systems. What differs is the gallon itself. The US liquid gallon is exactly 231 cubic inches, which became exactly 3.785411784 litres once the inch was fixed at 2.54 centimetres in 1959.

The imperial gallon took a different route, being defined by the volume of ten pounds of water and now fixed at exactly 4.54609 litres. Two exact definitions, arrived at independently, which is why the ratio between them is an untidy 1.2009 rather than anything memorable.

gallons = US quarts / 4
1 US gallon = 231 cubic inches = 3.785411784 L
4 qt -> 4 / 4 = 1 gallon
1 gallon = 4 quarts = 8 pints = 16 cups = 128 fl oz
imperial gallon = 4.54609 L, 20.09 percent larger

Why 231 cubic inches

The number looks arbitrary and is inherited. It comes from an English wine gallon defined as a cylinder seven inches across and six inches deep, which works out to about 231 cubic inches. The United States kept that gallon at independence; Britain abolished it in 1824 and built the imperial gallon instead.

The metric comparison, once

A US gallon is 3.785 litres, so four litres is 5.67 percent more than a gallon. That same 5.67 percent separates every US liquid measure from the round metric number nearest it, because they all descend from the same 231 cubic inch gallon while the metric ones descend from the litre.

How to use the quarts to gallons converter

A gallon is four quarts, and that ratio holds in both the US and imperial systems. The conversion is a division by four with no rounding error at all, because the quart was defined as a quarter of the gallon rather than measured against it. The complication is entirely in which gallon you mean.

A US liquid gallon is exactly 231 cubic inches. That is a strange-looking definition until you know it is inherited: the figure comes from an English wine gallon that the United States kept when Britain replaced it in 1824. Fixing the inch at 2.54 centimetres in 1959 turned it into exactly 3.785411784 litres.

Britain built a new gallon in 1824, defined by the volume of ten pounds of water, and that is the imperial gallon of exactly 4.54609 litres still used today. The United States never adopted it, so the two countries have been using the same word for two quantities a fifth apart for two centuries.

For cooking the gallon rarely appears, since a domestic recipe stops at quarts. It shows up in brining, batch stock, home brewing and anything preserved in bulk, where the working unit is the container rather than the measuring cup and a gallon is simply four cartons.

Two gallons, one word

The split is a historical accident that never got repaired. England used several gallons at once for centuries — one for wine, one for ale, one for corn — and the United States inherited the wine gallon of 231 cubic inches at independence. Britain abolished all of them in 1824 and defined a single imperial gallon in their place.

The imperial gallon was originally the volume of ten pounds of water at a specified temperature, and it is now fixed at exactly 4.54609 litres. Because the US kept the older wine gallon and Britain replaced it, the two are 20.09 percent apart, and neither country had any reason to move afterwards.

The tell is usually the country of publication rather than anything in the number. Where a figure is given in litres per hundred kilometres there is no ambiguity at all, which is part of why most of the world moved to that measure for fuel economy.

Where gallons still get used in a kitchen

Domestic recipes stop at quarts, so a gallon in a cooking context usually means a container rather than a measurement. Milk, water and stock are sold by the gallon in the United States, and a gallon jug is a familiar object in a way a gallon of measured liquid is not.

The exceptions are the preserving trades. Brining a turkey, building a batch of stock for a freezer, fermenting, or home brewing all work at gallon scale, and in all of them the quantity matters because the recipe is a concentration rather than a list. A brine at the wrong dilution cures at the wrong rate.

For anything measured by concentration, the gallon question becomes a real one. A brine recipe written for an imperial gallon and made up in a US gallon is 20.09 percent stronger than intended, which changes both the seasoning and the cure. Where a recipe gives a metric volume, that settles it.

Every US quarts value, worked out

39 common US quarts figures each get their own page, with the answer at full precision, the arithmetic, what rounding costs, and the nearest real-world reference point on the scale.

Questions people ask