A bunder is a unit of area in the Low Countries (Belgium and the Netherlands).
In the Netherlands, it was frequently used in the Achterhoek, Twente, and some parts of Drenthe to estimate areas of land, in particular in agriculture. Traditionally it had different values in various regions, but since the adaptation of the metric system it has been defined to be equal to one hectare.
In Belgium, a bunder was used as unit of area in the part of the country historically covered by the German Empire (i.e. east of the Schelde). In general, one bunder was 1/12 part of a mansus. During the French occupation (1796–1815) the old measurement standards were accurately converted to the metric system. A general standard like in the Netherlands (1 bunder = 1 hectare) has never been adopted in Belgium.