The kiloliter (kL), which is more commonly spelled kilolitre outside of the US, is a unit of metric measurement that refers to volume. It is 1000 times the size of a liter, which is a more recognizable unit of measurement for small amounts of liquid. The hierarchy of ascending measurements in liter form is as follows: milliliter, centiliter, deciliter, liter, decaliter, hectoliter and kiloliter. Other larger and smaller measurements are used far less frequently.
The use of liters derives from metric systems developed in France, and the English name for liter is a close derivative of the French term, litron. The litron first became popular for use in France after the French Revolution and the measurement quickly spread to other countries. Precise definition of the liter and its multiples shifted over time. Presently, a liter is .001 cubic meters, but for a while it was not quite equal to this number. It wasn’t until 1964 that the General Conference on Weights and Measures (GCWM) decided to set and standardize an exact relationship between kiloliters and cubic meters that made them equivalent.
Given this shift, defining the kiloliter as a precise fit with cubic meter measurements hasn’t always been easy. Moreover, this measurement isn’t used often unless large amounts of volume are being assessed. With standardization though, the kiloliter is exactly equal to a single cubic meter, which makes math calculations and conversions simpler.
For those people who don’t use metric measurements often, it also helps to get a sense of kiloiters as translated to standard volume measurements, which are frequently used in places like the US. The kiloliter is equal to 33,814.02 fluid ounces, 4,226.75 cups, 2,113.38 pints, 1,056.69 quarts, 264.17 gallons, and 35.32 cubic feet. It's useful to think of the size of a kiloliter in half-gallon milk cartons. Essentially, over 500 full milk cartons are required to equal a single kiloliter.
The size of this measurement suggests that it is not practical for most everyday measuring tasks. Instead, it could be used to accurately discuss volume of large quantities of liquid. Figuring the amount of water in a lake or a stream could employ kiloliters as a measurement, or sometimes may still use cubic meters instead. The number of gallons of water in a pool could also be converted to kiloliter form. Release of huge amounts liquid pollutants or chemicals might also be measured in kiloliters.
Basically, kiloliters are metric measure of volume and one is equal to 1000 liters or a single cubic meter. They tend to be used for gauging high volume levels, which means most people won’t use this unit frequently for daily activities. Kiloliters easily convert to other metric measurements, and with a little work, they can also be converted to standard measurement systems.