| Teraliters (TL) | Deciliters (dL) |
|---|---|
| 1 Teraliter | 10000000000000 dL |
| 2 Teraliters | 20000000000000 dL |
| 3 Teraliters | 30000000000000 dL |
| 4 Teraliters | 40000000000000 dL |
| 5 Teraliters | 50000000000000 dL |
| 10 Teraliters | 100000000000000 dL |
| 20 Teraliters | 200000000000000 dL |
| 25 Teraliters | 250000000000000 dL |
| 50 Teraliters | 500000000000000 dL |
| 100 Teraliters | 1 × 1015 dL |
| Reference | Teraliters (TL) | Deciliters (dL) |
|---|---|---|
| A teaspoon | 5 × 10-15 TL | 0.05 dL |
| A can of soft drink | 3.3 × 10-13 TL | 3.3 dL |
| A wine bottle | 7.5 × 10-13 TL | 7.5 dL |
| A bathtub | 1.5 × 10-10 TL | 1500 dL |
| An Olympic swimming pool | 0.0000025 TL | 25000000 dL |
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.
The decilitre is a unit of volume equal to one tenth of a litre, or one hundred millilitres. Its symbol is dL, and the lower-case dl is common. Although the deci prefix has fallen out of use almost everywhere else, the decilitre is alive in two quite separate places: the Nordic kitchen and the clinical laboratory.
Scandinavian cooking is built on it. Swedish, Norwegian, Danish and Finnish recipes give flour, sugar, milk, cream and stock in decilitres, and a set of nested measuring cups marked in decilitres and fractions of one is standard kitchen equipment. Where an English recipe says a cup and an Italian one weighs the flour, a Nordic recipe asks for three decilitres, which is both faster and more repeatable than either.
Switzerland uses it for drink. Wine in a Swiss restaurant is ordered by the decilitre, so a glass is one or two and a carafe five, and the measure is printed on the glass. Because a decilitre is close to the volume of a modest wine pour, the unit gives customers an exact quantity rather than a description, which is what licensing law in several cantons requires.
Clinical chemistry is its other stronghold, and there it decides how a whole country reads its blood tests. Glucose, cholesterol and creatinine are reported in milligrams per decilitre in the United States, Japan, France, Italy and Spain, and in millimoles per litre in Britain, Canada, Australia and the Nordic countries. A fasting glucose of 100 milligrams per decilitre is 5.6 millimoles per litre, and the same person's result therefore looks entirely different depending on the laboratory.
Haemoglobin crosses the divide. It is reported in grams per decilitre almost everywhere, so a normal adult value of 13 to 17 grams per decilitre reads the same in most of the world. The decilitre survives in these places because a hundred millilitres of blood is a convenient reference quantity and because changing an established reporting unit risks misreading a result.
For scale, a decilitre is a small glass of water, half a mug of coffee, or the volume of a large egg and a half. It converts to 3.38 United States fluid ounces or 3.52 imperial fluid ounces, and to a little under half a United States cup, which is why converted Nordic recipes rarely come out in round numbers.
One decilitre equals 100 millilitres, 0.1 litres, about 3.38 US fluid ounces, or about 3.52 imperial fluid ounces.