Planck Volume (L³, Natural Units) to Gallon (gal, British Imperial Liquid And Dry)

The traditional English apothecaries' system defines weights, not volumes. However, there was apothecaries' system for volumes too, though less commonly used. Before introduction of the imperial units, all apothecaries' measures were based on the wine gallon which later became the base of U.S. liquid gallon.

In addition to five official apothecaries' units pint, fliud ounce, fluid dram, fluid scruple, and minim, there was a set of unofficial but widely used units for various spoon and glass sizes. We list them here too.

In 1858 apothercaries' system was officially abolished in in the U.K. in favour of the standard Avoirdupois system. In the United States the apothecaries' system remained in use until 1971, when it was officially abolished in favor of the metric system.