Outside of the United States, the metric system is theoretically the standard system of measurements for all countries; however, nations have often informally retained a few traditional measurements. For example, Canadians still work in pounds rather than kilograms; and, in Europe, the Swedes have kept their mil to refer to distance, while many British people still speak in terms of miles. Both of these stand opposed to the metric system of distance measurement, the metre and the kilometre (1000 metres).
Etymologically, both the British mile, the Swedish mil, and all other similar systems of measurement have their origin in an older Roman unit of distance, the “mille passum” – or “thousand steps.” The Roman mille referred to the space a man would cover in a thousand footsteps. From this also descended the Danish mil, the German meile, the Russian milya, and the Croatian milja, among others; despite their origin in the same Roman phrase, many of these units varied significantly in terms of their actual definition. The German meile was 24,000 German feet, or almost five imperial miles.
– The Mile –
Miles are the traditional imperial unit for measuring long distances, and are made up of 5280 feet (unless one is speaking of nautical miles, which are 6076 feet; nautical miles are the standard of distance used at sea). In previous centuries this was coupled with an even longer unit of measurement, leagues, which were made up of three miles.
Miles were a British invention of the 16th century, officially established by Elizabeth I. Although this was not the first use of the mile in customary English, it was the first time that the unit was officially defined, so that all English reports and surveys could be held to a single standard of measurement. Thus, for a time, separate definitions of the Scottish mile and the Irish mile also existed, though they were later replaced by the English mile. Both Irish and Scottish miles were longer than the English mile.
– The Mil –
The mil is a Scandinavian unit of measurement, still used in Norway and especially in Sweden despite those countries’ official adoption of the metric system well over a century ago. Traditionally, it was equivalent to 36,000 feet, or about 6.8 English miles, and was sometimes referred to as the Swedish “long mile.” Note that the Swedish foot was also very slightly longer than the English imperial foot; standard popular history has it that this was because different kings insisted on having the foot standardized according to the differing lengths of their own individual feet.
The Scandinavian countries are unusual in that, rather than officially abolishing their older distance measurements despite their continued use in everyday conversation, their traditional units were legally redefined to accommodate new metric units. For this reason, when the Swedish mil is used in conversation today, Swedes aren’t actually referring to the traditional measurement of 7 miles, but to an officially fixed “long kilometre,” exactly 10 kilometres or 10,000 metres in length. Similar reforms occurred in the other Scandinavian countries, Finland and Norway.
– Conversion –
Because the Swedish mil has been redefined in terms of the kilometre, conversions between British miles and Swedish mils is now effectively the same as between miles and kilometres: there are 1.6 kilometres per mile, and 0.16 Swedish mils per mile. (Alternatively, there are 0.62 miles in a kilometre, and 6.2 miles in a Swedish mil.