Convert Tun (tun) to Acre-Foot (US Survey) (ac*ft (US)) instantly.
About these units
Tun (tun)
A tun is a historical large cask unit commonly used in the wine and brewing industries, typically defined as 252 imperial gallons, or roughly 954 liters. It represented one of the largest standardized cask sizes in medieval and early modern Europe. Originally used for transporting wine, ale, and oil, the tun played an important role in commerce and maritime trade. Because taxes and tariffs were often levied per tun, its definition became central to economic regulation. The size also reflected the maximum volume that could be reliably transported in wooden casks without structural failure. Though obsolete today, the tun provides valuable insight into historical logistics, taxation, and the evolution of standardized container sizes in European trade networks.
Acre-Foot (US Survey) (ac*ft (US))
The US survey acre-foot differs extremely slightly from the international acre-foot due to the slight difference between the survey foot and the international foot. While the distinction is negligible in most contexts, it is important in surveying, legal water rights, and long-term hydrological accounting, especially in regions where large historical datasets were recorded using US survey measures. This variant highlights how even subtle unit differences can have major implications when dealing with huge volumes over long timescales, such as state water budgets and inter-state compacts.