| Pints (pt) | Teraliters (TL) |
|---|---|
| 1 Pint | 5.6826125 × 10-13 TL |
| 2 Pints | 1.1365225 × 10-12 TL |
| 3 Pints | 1.70478375 × 10-12 TL |
| 4 Pints | 2.273045 × 10-12 TL |
| 5 Pints | 2.84130625 × 10-12 TL |
| 10 Pints | 5.6826125 × 10-12 TL |
| 20 Pints | 1.1365225 × 10-11 TL |
| 25 Pints | 1.420653125 × 10-11 TL |
| 50 Pints | 2.84130625 × 10-11 TL |
| 100 Pints | 5.6826125 × 10-11 TL |
| Reference | Pints (pt) | Teraliters (TL) |
|---|---|---|
| A teaspoon | 0.00879877 pt | 5 × 10-15 TL |
| A can of soft drink | 0.580719 pt | 3.3 × 10-13 TL |
| A wine bottle | 1.31982 pt | 7.5 × 10-13 TL |
| A bathtub | 263.963 pt | 1.5 × 10-10 TL |
| An Olympic swimming pool | 4399385 pt | 0.0000025 TL |
The pint in the imperial system is a unit of volume equal to exactly 568.26125 millilitres. Its symbol is pt. It is twenty imperial fluid ounces, an eighth of an imperial gallon, and half an imperial quart. It is the only imperial unit that most people in Britain and Ireland still use every week, and it survives because it is the legal measure for draught beer.
That legal status is precise. Draught beer and cider in the United Kingdom may be sold only in third-pints, half-pints and multiples of half a pint, and the glass itself must carry a verification mark certifying that it holds the stated measure. Publicans can be prosecuted for short measure, so the pint is one of the few units in daily life whose accuracy is actively policed.
Milk keeps the second foothold. Milk sold in returnable glass bottles may still be measured in pints, which is why doorstep deliveries are ordered by the pint while supermarket cartons carry litres. That split is a useful illustration of how metrication proceeded in Britain: it changed the shops and left the traditions alone.
The American pint is a different quantity and the difference is large. A United States liquid pint is 473 millilitres against the imperial 568, so a British pint is about a fifth bigger, and a traveller who orders a pint in New York receives noticeably less than one in Dublin. The American mnemonic that a pint's a pound the world around works only for the American pint; a British pint of water weighs a pound and a quarter.
That weight relationship was once the definition. The imperial system was built so that a gallon of water weighed ten pounds, which makes a pint weigh exactly a pound and a quarter, and the older British rhyme says so directly. Since 1985 the pint has been defined from the metric gallon instead, but the relationship still holds closely enough to be a useful check.
Below the pint the imperial chain runs to the gill at a quarter of a pint and the fluid ounce at a twentieth. Above it come the quart and the gallon. None of these steps is decimal, which is the reason the pint is now the only survivor: it is the one member of the chain that people handle directly, and the rest of the arithmetic has quietly moved to litres.
One imperial pint equals 568.26125 millilitres, 20 imperial fluid ounces, 0.125 imperial gallons, or about 1.201 US liquid pints.
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.