| Furlongs (fur) | Meters (m) |
|---|---|
| 1 Furlong | 201.168 m |
| 2 Furlongs | 402.336 m |
| 3 Furlongs | 603.504 m |
| 4 Furlongs | 804.672 m |
| 5 Furlongs | 1005.84 m |
| 10 Furlongs | 2011.68 m |
| 20 Furlongs | 4023.36 m |
| 25 Furlongs | 5029.2 m |
| 50 Furlongs | 10058.4 m |
| 100 Furlongs | 20116.8 m |
| Reference | Furlongs (fur) | Meters (m) |
|---|---|---|
| A sheet of A4 paper (long side) | 0.00147638 fur | 0.297 m |
| Average adult human height | 0.00845065 fur | 1.7 m |
| A football pitch (length) | 0.521952 fur | 105 m |
| A marathon | 209.75 fur | 42195 m |
| Height of Mount Everest | 43.9881 fur | 8849 m |
The furlong is a unit of length equal to 220 yards, 660 feet, or exactly 201.168 metres. It is one eighth of a mile and ten chains.
The name is a contraction of the Old English furh lang, meaning furrow long, and describes the distance a team of oxen could plough before needing rest. That practical origin fixed the length of a medieval strip field, and the furlong therefore predates the mile's English definition. When the Roman mile of 5000 feet was reconciled with English land measurement, the mile was lengthened to 5280 feet so that it would contain a whole number of furlongs. The awkward figure that generations of schoolchildren have memorised is a direct consequence of preserving the older agricultural unit.
Horse racing is where the furlong remains in active daily use. Race distances in Britain, Ireland, the United States and much of the racing world are stated in miles and furlongs, so a race described as one mile two furlongs covers 2010 metres. Sectional times are recorded furlong by furlong, and commentary is built around the unit. Distance markers along the rail count down the remaining furlongs to the finish.
The furlong's relationship to area explains its persistence in older records. An acre was originally defined as one furlong long by one chain wide, the area a team could plough in a day. This is why an acre is a long thin rectangle rather than a square, and why its modern value of 43,560 square feet looks arbitrary.
Outside racing the unit is largely archaic, though it appears in some historical land deeds and in the occasional legal description. Computing folklore keeps it alive in the furlong per fortnight, a deliberately absurd unit of speed used to make a point about dimensional analysis.
It is the reason the acre has the shape it does. An acre was defined as one furlong long by one chain wide, 220 yards by 22, and that long thin rectangle is exactly what a team of oxen could plough in a day without turning more often than necessary. The proportion of ten to one is preserved in the ridge and furrow patterns still visible from the air across the English Midlands, and in field boundaries that have outlasted every plough that made them. The furlong therefore survives less as a measurement than as a shape written into the landscape.
One furlong equals 220 yards, 10 chains, one eighth of a mile, or 201.168 metres.
The metre is the base unit of length in the International System of Units, written m. Every other SI length unit is defined as a multiple or fraction of it, and units of area, volume, speed and many others are built from it in turn.
Its definition has been revised four times, each revision replacing a physical object with something more reproducible. The French Academy of Sciences proposed in 1791 that the metre should be one ten-millionth of the distance from the North Pole to the equator along the meridian through Paris. Surveying that arc took six years and produced a small error, since the Earth is not a perfect sphere. In 1889 the definition moved to a platinum-iridium bar held at Sèvres, near Paris, with copies distributed to signatory nations. In 1960 it was redefined as 1,650,763.73 wavelengths of orange-red light emitted by krypton-86.
The current definition dates from 1983 and is unusual in that it fixes a different quantity. The speed of light in vacuum is defined as exactly 299,792,458 metres per second, and the metre follows as the distance light travels in 1/299,792,458 of a second. Light speed is therefore no longer measured; it is a defined constant, and improvements in measurement now refine the metre rather than the speed.
The unit is used worldwide for building dimensions, athletics tracks, swimming pools, water depth, fabric and rope. Only a small number of countries retain imperial units for general purposes, and even there the metre dominates science and medicine.
Everyday reference points help fix the scale. A standard interior door is roughly two metres tall. A single stride for an adult is close to three quarters of a metre, which is why pacing is a workable rough measure of distance. The width of a single traffic lane is between three and three and a half metres in most countries.
One metre equals 100 centimetres, 1000 millimetres, or 0.001 kilometres. It is approximately 3.28084 feet, or 39.3701 inches.