Metric to US Weight Units
This calculator will help you convert between US weight units and Metric weight units. This is useful when using a recipe created in one unit and brewing it in the other. Note that the US weight units are International Avoirdupois Ounces, which measure weight as opposed to Fluid Ounces, which measure volume.
(Almost) Useless Trivia
50 Kilograms of hops has its own unit, called the Zentner.