(from German Haken, wooden plow), a tax unit in Estonia and Latvia in feudal times that was used in determining the size of duties to the feudal lord and the state.

The most widespread form of hak was the so-called peasant hak, which in northern Estonia consisted of an average of 8-12 hectares of sown land. In addition, the state authorities in the 17th and 18th centuries began to make use of the revision hak, which usually was larger than the peasant hak. The accounts of the peasants with the pomeshchiki (landlords) were done according to peasant hak; taxes were paid to the state according to revision hak, which was calculated on the basis of the number of tax days in the week or the number of peasants capable of work, or according to the sum of the peasant debt in money terms. Hak ceased to be used at the end of the 19th century.