|Unit system||imperial/US customary units|
|1 furlong in ...||... is equal to ...|
|imperial/US units||220 yd|
|metric (SI) units||201.1680 m|
The unit was first used in the ninth century at the latest. The word "furlong" comes from Old English words furh ("furrow") and lang ("long"). Originally it was the length of the furrow in one acre of a ploughed field. An acre is an area that is one furlong long and one chain wide. For this reason, the furlong was once also called an acre's length. Around the year 1300, England standardized the furlong as 40 rods or 660 feet.
The furlong was abolished for official use in the UK in 1985. It is still occasionally seen on road signs in Myanmar.
Distances for horse racing in the UK, Ireland, and Canada are still given in miles and furlongs. The unit is not used otherwise. It is considered to be an archaic unit.
The proverb one furlong per fortnight means to express something in as obscure and little-used units as possible. (A fortnight is two weeks, or fourteen days). The proverb itself means speed, and is the same as 0.000166309524 m/s or 0.17 mm/s.