Volume Converter

How to use the volume converter

Type a number, pick the unit it is already in, pick the unit you want, and the answer updates as you type. Every unit in the list declares how many liters it is worth, so any pair converts by going through that base: milliliters to imperial pints, cubic meters to US gallons, teaspoons to liters, all 156 ordered pairs the thirteen units can form.

Swap flips the two dropdowns and keeps the value, which is the quickest way to sanity-check a result in reverse. The list covers three groups: the metric three (milliliter, liter, cubic meter), the full US customary ladder from teaspoon up to gallon, and three imperial measures that share names with US ones without sharing their size. That last group is where most volume mistakes are made, so it is worth knowing what separates them.

A US pint is 473.176473 mL and an imperial pint is 568.26125 mL, which makes the British pint about 20 percent larger. Pour a US recipe into a UK pint glass and you are a fifth short. The gallons diverge the same way: 3.785411784 L against 4.54609 L, so a US gallon is roughly 83 percent of an imperial one, or put the other way, the imperial gallon is about 17 percent bigger.

The counterintuitive part is the fluid ounce, which runs the opposite direction. A US fluid ounce is 29.5735295625 mL and an imperial fluid ounce is 28.4130625 mL, so the US ounce is the larger of the two, by about 4 percent. The pints still differ because of how many go into one: 16 ounces to a US pint, 20 to an imperial pint.

Every factor behind this tool is an exact definition, not an approximation. The US gallon is exactly 231 cubic inches, and since the inch has been exactly 25.4 mm since 1959 that pins it at 3.785411784 L with no rounding anywhere; the smaller US units divide straight down from it.

Two things the tool deliberately does not do: it does not handle US dry pints and quarts, which are a separate and larger set used for produce, and it does not convert volume into weight.

Which cup does your recipe mean?

Cup is the least trustworthy word in the whole list. The US customary cup this tool uses is one sixteenth of a US gallon, or 236.5882365 mL. The FDA defines a different cup for nutrition labels: a flat 240 mL, alongside 15 mL for a tablespoon, 5 mL for a teaspoon and 30 mL for a fluid ounce, under 21 CFR 101.9.

So the serving size printed on a cereal box is not quite the cup in your cupboard. Australia, New Zealand and Canada use a metric cup of 250 mL, which is why four of them fill a liter exactly and why a metric cup is about 5.7 percent larger than the US customary one. Australia also standardized a 20 mL tablespoon under AS 1325 — four teaspoons, not three.

The formula, worked line by line

Each unit stores one number: how many liters it is worth. A conversion between any two of them is a pivot through that base — multiply into liters, divide out into the target — so one expression covers every pair in the table.

liters = value × from.perBase
result = liters ÷ to.perBase
result = value × from.perBase ÷ to.perBase
US pint → imperial pint: value × 0.473176473 ÷ 0.56826125

Because every perBase here is an exact definition, the arithmetic carries no accumulated error and only the display rounds. That matters at the extremes: converting cubic meters to teaspoons multiplies by roughly 202,884, so a factor rounded even in the sixth decimal would show up in the answer. The one place to be careful is chaining conversions by hand through intermediate rounded values — go through the base once, not through three tables.

Questions people ask