A morgen was a unit of measurement of land area in Germany, the Netherlands, Poland, Lithuania and parts of the Dutch Overseas Empire, such as South Africa. The size of a morgen varies from 1⁄2 to 2+1⁄2 acres (2,000 to 10,100 m²). It was also used in Old Prussia, in the Balkans, Norway and Denmark, where it was equal to about two-thirds acre (2,700 m²).

The word is identical with the German and Dutch word for "morning" because, similarly to the Imperial acre, it denoted the acreage that could be furrowed in a morning's time by a man behind an ox or horse dragging a single-bladed plough.^{[citation needed]} The morgen was commonly set at about 60–70% of the tagwerk (German for "day work") that referred to a full day of ploughing. In 1869, the North German Confederation fixed the morgen at a one-quarter hectare (2,500 m²),^[1] but in modern times most farmland work is measured in full hectares. The next lower measurement unit was the German "rute" or Imperial rod, but the metric rod length of 5 metres (16 ft) never became popular.

The following table shows an excerpt of morgen sizes as used in Germany — some morgen were used in a wider area and thus had proper names. The actual area of a morgen was considerably larger in fertile areas of Germany, or in regions where flat terrain prevails, presumably facilitating tilling. The next lower measurement unit to a morgen was usually in "Quadratruten" square rods.

The Polish terms for the unit were morga, mórg, jutrzyna, the latter being a near-literal translation into old Polish.

The term "morgen" was used in the Austrian Kingdom of Galicia and Lodomeria where 1 morgen was equal to 2⁄3 acre (2,700 m²).^[2]

Until the advent of metrication in the 1970s, the morgen was the legal unit of measure of land in three of the four pre-1995 South African provinces – the Cape Province, the Orange Free State and the Transvaal. In November 2007 the South African Law Society published a conversion factor of 1 morgen = 0.856 532 hectares to be used "for the conversion of areas from imperial units to metric, particularly when preparing consolidated diagrams by compilation".^[3]

• Arpent
• Dutch units of measurement
• German obsolete units of measurement
• List of unusual units of measurement