Convert Drop (drop) to Acre-Foot (US Survey) (ac*ft (US)) instantly.
About these units
Drop (drop)
The drop is one of the oldest fluid measures and originally referred simply to the amount of liquid that naturally forms at the end of a dripping vessel. Because drop size depends on viscosity, surface tension, temperature, and orifice size, early medicine found drops inconsistent and unreliable. Modern medicine and chemistry sometimes define a drop as 0.05 mL, but this is only a convention used for standardized droppers—real drops can vary significantly. Despite its imprecision, the drop survives in everyday language, aromatherapy, essential oils, and household instructions ("add a few drops"). It exemplifies humanity's earliest attempts to quantify small volumes before scientific instrumentation enabled precise micro-measurement.
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.