The U.S. dollar was the world's first decimal currency, and in the United States, the government, scientific and business institutions use the metric system. Yet in everyday life, the English system (aka the U.S. customary system) remains unchallenged, the 2 liter soda bottle notwithstanding. The English system is human-scale, works well for fractions and is entrenched in American culture and life. The metric system, however, is consistent, comprehensive, logical and used worldwide.

Metric is Logical

The metric system uses the base of 10 for all measurements. Higher-level units are simply lower-level units multiplied by 10. Lower-level units are divided accordingly. The same prefix is signifies a multiplication or division by the same factor for all measures. One example is kilo: A kilometer is 1,000 meters, and a kilogram is 1,000 grams. Another is milli: A milliliter is 0.001 of a liter and a millivolt is a 0.001 of a volt. The conversion from the lower to the higher level is quick and easy.

The English system, although partially based on the multiples of 12, has no coherent logic. A pound is 16 ounces, but a foot is 12 inches, a gallon is 8 pints and a mile is 1,760 yards. Students must learn the name of each unit separately.

Metric Rules the World

Most countries in the world use the metric system, as do most international corporations and international and national scientific communities, including in the U.S. The U.S. converting to an all-metric system would make transfer of goods, information and technology easier and simpler. The English system is used in the U.S. only. Although vestiges of the similar imperial system remain in the United Kingdom and its former colonies, there are confusing differences between the two.

English is Human-Scale

The English measures developed in a natural way as people went about their tasks. The measures are human-scale and, once learned, easy to use. A pint of beer is easier to order than 500ml, and a half-pound is easier to think of than 250g. Many English system measures work well with fractions, which are convenient in everyday life. On the other hand, metric measures might seem unwieldy and complex at first, although the Europeans happily say "half a liter" and "quarter of a kilo" rather than using the technically correct 500ml or 250g, respectively.

English Rules the U.S.

The cost of going metric for a country as populous and the economy as large as that of the U.S. would be huge. Doing so would confuse and disorient many people, especially the aged and less educated. From car speedometers and road signs to calibrating thermometers, bottle, barrel and box sizing, the financial and social cost of metrication might be just too much for the country to bear.

Simply by entrenchment, the English measures system might be here to stay. The U.S. market is large enough to support the production of its own packaging and manuals while the opposition to metrication is still strong. A parallel use of two systems likely will continue for some time.