Conversion from Microliters to Deciliters

Information about the Microliter (µL)

The microlitre is a unit of volume equal to one millionth of a litre, written µL. It is exactly one cubic millimetre. It is the working unit of the molecular biology laboratory and of clinical haematology, and almost every quantity in modern biological science that is not a mass or a concentration is a number of microlitres.

Pipetting is what defines it in practice. Adjustable micropipettes are named after their maximum volume in microlitres, so a bench holds instruments of 2, 20, 200 and 1000, and a researcher's day consists largely of moving microlitres from one tube to another. A polymerase chain reaction is typically assembled in twenty to fifty microlitres, and a whole experiment may use less liquid than a teaspoon holds.

Blood counts are reported against it. White cells number between four thousand and eleven thousand per microlitre in a healthy adult, platelets between a hundred and fifty thousand and four hundred thousand, and red cells about five million. Those reference ranges are among the most widely used numbers in medicine, and all of them are counts within a cube one millimetre on a side.

Diagnostics has driven the volumes down. A modern blood glucose meter needs about half a microlitre of blood, which is why a finger-prick sample is enough where an earlier generation of instruments needed a syringe. Point-of-care analysers, lateral flow tests and microfluidic cartridges are all designed around the smallest sample a patient can be asked to give.

Analytical chemistry uses the same scale. Injection volumes in liquid chromatography run from one to twenty microlitres, gas chromatography uses one or less, and mass spectrometry samples are prepared in tens. Because the analytical signal depends on the amount injected, the accuracy of a microlitre-scale measurement sets the accuracy of the whole result.

The identity with the cubic millimetre is a genuine convenience. Haematology once reported cell counts per cubic millimetre and now reports them per microlitre, and the numbers did not change at all, because the two units are the same. That is a rare case of a unit change in medicine that required no re-education and produced no errors.

One microlitre equals 1 cubic millimetre, 0.001 millilitres, 0.000001 litres, or about 0.0000338 US fluid ounces.

Information about the Deciliter (dL)

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.