Conversion from Gallons to Nanoliters

Information about the Gallon (gal)

The gallon in the imperial system is a unit of volume equal to exactly 4.54609 litres. Its symbol is gal. It contains four quarts, eight pints and 160 imperial fluid ounces, and it is about a fifth larger than the United States gallon, a difference that causes more confusion than any other single discrepancy between the two systems.

Its original definition was elegant. The Weights and Measures Act of 1824 fixed the imperial gallon as the volume occupied by ten pounds of distilled water at sixty-two degrees Fahrenheit under a barometric pressure of thirty inches of mercury. That tied liquid measure directly to the avoirdupois pound, so a gallon of water weighed ten pounds and a pint weighed a pound and a quarter. In 1985 the definition was replaced by the exact metric figure, but the old relationship still holds to within a fraction of a per cent.

Fuel economy keeps it in daily use. British and Irish drivers describe consumption in miles per gallon even though fuel has been sold in litres since the 1990s, and the figure is an imperial one. The same car scores about twenty per cent higher in British miles per gallon than in American, purely because the gallon is larger, which is why cross-Atlantic comparisons of efficiency are meaningless unless the gallon is specified.

Legal use in Britain is now narrow but real. Draught beer and cider must be sold in pints, half pints or third pints, and milk in returnable containers may be sold in pints, which keeps the whole imperial chain alive by keeping its smallest working member alive. Several Caribbean territories still sell motor fuel by the imperial gallon.

The difference from the American gallon is worth stating plainly. One imperial gallon is 4.546 litres and one United States gallon is 3.785, so an imperial gallon is 1.2 United States gallons. Recipes, fuel figures, tank capacities and chemical dilutions all break if the wrong one is assumed, and the error is large enough to matter but small enough to look plausible.

Below it the chain runs quart, pint, gill and fluid ounce, each a quarter or a fifth of the one above rather than a decimal step. That structure was designed for dividing a container by halving it repeatedly, which is a practical merit when pouring and a serious nuisance when calculating.

One imperial gallon equals 4.54609 litres, 8 imperial pints, 160 imperial fluid ounces, or about 1.201 US gallons.

Information about the Nanoliter (nL)

The nanolitre is a unit of volume equal to one billionth of a litre, written nL. It is a thousandth of a microlitre, and a nanolitre of water has a mass of one microgram. It is the scale at which liquid handling stops being a matter of pipettes and becomes a matter of engineered channels, printed droplets and acoustic pulses.

Microfluidics is built here. A lab-on-a-chip moves samples through channels a few tens of micrometres wide, so the volume inside any one segment is measured in nanolitres, and a whole analysis may consume less than a microlitre. Working at this scale changes the physics as well as the quantity: surface tension dominates gravity, flows stay orderly rather than turbulent, and mixing has to be engineered rather than assumed.

Digital polymerase chain reaction shows what the scale buys. A sample is divided into around twenty thousand droplets of roughly one nanolitre each, every droplet is amplified separately, and the number that come out positive gives an absolute count of target molecules rather than a relative measurement. Dividing a microlitre into thousands of countable compartments is only possible because a nanolitre is small enough to hold either one target molecule or none.

Drug screening moves liquid without touching it. Acoustic dispensers use a focused sound pulse to eject droplets of two and a half nanolitres from an open well, with no tip and therefore no cross-contamination and no plastic waste. A screening plate of fifteen hundred wells can be filled with distinct compounds in a few minutes at this volume.

Printing and spotting work at the same magnitude. A microarray spot holds between half a nanolitre and five, an inkjet droplet is a few picolitres so a nanolitre is several hundred drops, and single-cell platforms encapsulate individual cells in droplets of this size because a mammalian cell occupies only a few picolitres.

Handling nanolitres reliably is mostly a fight against evaporation. A one-nanolitre droplet exposed to air can lose a measurable fraction of itself in seconds, so devices at this scale work under oil, in sealed channels or in humidity-controlled enclosures, and that constraint shapes the instruments more than the dispensing itself does.

One nanolitre equals 0.001 microlitres, 0.000001 millilitres, 0.001 cubic millimetres, or 1,000,000 cubic micrometres.