Volume units: metric and imperial
Liters, cubic meters, gallons and pints at a glance
The SI unit of volume is the cubic metre (m³). In everyday life, the liter (l) is the more practical unit – it is not an official SI base unit, but it is accepted by the International Bureau of Weights and Measures (BIPM) and defined as 1 liter = 1 cubic decimeter = 0.001 m³. Water has a density of exactly 1 kg/l at 4°C, which directly links liters and kilograms for water. This elegant connection was deliberately chosen when the metric system was designed.
In English-speaking countries, gallons and pints (US measurements) are ubiquitous. Fuel in the US is billed in gallons (1 US gallon = 3.785 l), and recipes use cups and pints. Important: there are US and British versions of these units that differ. The British (imperial) gallon is larger: 4.546 l compared to 3.785 l (US). Accordingly, the British pint (568 ml) is larger than the US pint (473 ml). A pint of beer in a British pub is therefore about 20% more than a pint in an American bar. Our converter uses the US variants.
In industry and engineering, cubic meters and milliliters are essential: natural gas is measured in m³ or kWh (1 m³ of natural gas ≈ 10 kWh calorific value), and pharmaceutical dosages in ml or microliters (µl). Converting volume to mass always requires the density of the respective liquid – for water (1 kg/l at 4°C) the conversion is simple, while for oil (approx. 0.85 kg/l) or alcohol (approx. 0.79 kg/l) it varies.
In cooking and baking, conversion questions frequently arise when following international recipes. American recipes use cups, tablespoons (tbsp) and teaspoons (tsp): 1 cup = 240 ml, 1 tbsp = 15 ml, 1 tsp = 5 ml. British recipes occasionally use fluid ounces (fl oz): 1 fl oz (US) = 29.57 ml, 1 fl oz (UK) = 28.41 ml. For baking recipes where precision matters, it's best to weigh ingredients in grams rather than use volume measurements, since the density of e.g. flour can vary depending on sifting and packing.
Fuel prices illustrate why volume conversion is practically relevant: in the US, gasoline costs about $3–4 per gallon. To compare with German prices, divide by 3.785 (gallon to liter) and convert the dollar amount to euros. A US price of $3.50/gallon equals about $0.92/liter – at an exchange rate of $1.10/€ that would be about €0.84/liter, considerably cheaper than in Germany (typically €1.60–1.90/liter).