| Centiliters (cL) | Teraliters (TL) |
|---|---|
| 1 Centiliter | 1 × 10-14 TL |
| 2 Centiliters | 2 × 10-14 TL |
| 3 Centiliters | 3 × 10-14 TL |
| 4 Centiliters | 4 × 10-14 TL |
| 5 Centiliters | 5 × 10-14 TL |
| 10 Centiliters | 1 × 10-13 TL |
| 20 Centiliters | 2 × 10-13 TL |
| 25 Centiliters | 2.5 × 10-13 TL |
| 50 Centiliters | 5 × 10-13 TL |
| 100 Centiliters | 1 × 10-12 TL |
| Reference | Centiliters (cL) | Teraliters (TL) |
|---|---|---|
| A teaspoon | 0.5 cL | 5 × 10-15 TL |
| A can of soft drink | 33 cL | 3.3 × 10-13 TL |
| A wine bottle | 75 cL | 7.5 × 10-13 TL |
| A bathtub | 15000 cL | 1.5 × 10-10 TL |
| An Olympic swimming pool | 250000000 cL | 0.0000025 TL |
The centilitre is a unit of volume equal to one hundredth of a litre, or ten millilitres. Its symbol is cL, and the lower-case cl is also used. Unlike most centi-prefixed units it has a real commercial life, because it happens to be the size that suits drink labelling, and in several countries it is the form printed on almost every bottle.
Drink containers are its main employment. In France, Belgium, Italy and Spain a wine bottle is labelled 75 cL, a beer 33 or 50 cL, a soft drink 33 cL, and a spirits miniature 5 cL. The same containers carry 750 ml and 330 ml in Britain, Germany and most of the English-speaking world, which is why identical bottles appear to bear different numbers depending on where they were filled.
Bar measures follow the same split. A standard spirit serving is 4 cL in France and 2 or 4 cL in Germany and Austria, while Britain pours 25 or 35 millilitres and the United States uses fluid ounces. European cocktail recipes are written in centilitres throughout, so a classic proportion of six parts to three to one appears as 6 cL, 3 cL and 1 cL, which reads more cleanly than the millilitre equivalents.
There is no legal difference between the forms. European Union labelling rules accept millilitres, centilitres and litres, so the choice is a matter of national typographic habit rather than of regulation. Where centilitres are used, the number on a bottle stays between one and a hundred for every ordinary container size, which is exactly the range a prefix is supposed to deliver.
The unit is also easy to picture. Ten millilitres is two teaspoons, a generous mouthful of water, or the dose measure supplied with a bottle of cough syrup. A tablespoon is one and a half centilitres, an espresso is about three, and a wine glass poured to a standard measure is twelve to fifteen.
Converting between systems needs some care because a centilitre falls between the two customary small measures. It is 0.338 United States fluid ounces and 0.352 imperial fluid ounces, so neither reads as a round number, and drink volumes converted between Europe and North America almost always end up rounded rather than exact.
One centilitre equals 10 millilitres, 0.01 litres, about 0.338 US fluid ounces, or about 0.352 imperial fluid ounces.
The teralitre is a unit of volume equal to a thousand gigalitres, or 1,000,000,000,000 litres. Its symbol is TL. It is exactly one cubic kilometre, and that is how the quantity is almost always written, because at this scale what is being measured is no longer a container but a piece of the planet.
Lakes are the obvious application. Lake Baikal holds about 23,600 cubic kilometres of fresh water, more than any other lake on earth, and Lake Superior about 12,100. Those two figures alone amount to a fifth of the world's unfrozen surface fresh water, which is the kind of statement the unit exists to make.
Rivers are described by the volume they move rather than by what they hold. The Amazon discharges roughly 6600 cubic kilometres a year into the Atlantic, more than the next several rivers combined, and total human withdrawal of fresh water from all sources runs to about 4000 cubic kilometres a year. Setting those two numbers side by side in the same unit is one of the clearest ways to state the scale of water use.
Ice is measured here too, and the numbers are larger again. The Greenland ice sheet contains close to 2.9 million cubic kilometres, and in recent decades it has been losing a few hundred each year, a figure that converts directly into millimetres of sea level because the ocean's surface area is known. The Antarctic sheet is an order of magnitude larger still.
The ocean itself sets the ceiling. All the seawater on earth amounts to about 1.335 billion cubic kilometres, so a single teralitre is roughly one billionth of it. Below the ocean, the largest managed water bodies are engineered reservoirs, and even the biggest of those hold only a few tens of cubic kilometres.
In practice the name teralitre is rare and the cubic kilometre is standard. Hydrology, glaciology and climate science all use km³, and a figure given in teralitres is more likely to come from a water utility extending its own gigalitre scale upward than from a scientific source. The two are identical, so no conversion is needed, only recognition.
One teralitre equals 1,000,000,000,000 litres, 1,000,000,000 cubic metres, 1 cubic kilometre, or 1000 gigalitres.