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This difficult-to-pronounce system of measurement (av-wah-doo-PWAH) is used for ordering and purchasing some pharmaceutical products and for weighing patients.

In this system, which means goods sold by weight, the solid measures or units of weight include grains (gr), ounces (oz), and pounds (lb). One ounce equals 480 gr, and 1 lb equals 16 oz or 7,680 gr. Note that the apothecaries' pound equals 12 oz, but the avoirdupois pound equals 16 oz.


Avoirdupois system conversions

The following examples show how to perform conversions in the avoirdupois system:

  • How many pounds equal 32 oz? One pound equals 16 oz; therefore, 2 lb equal 32 oz.

  • How many ounces equal 7,680 gr? One ounce equals 480 gr; therefore, 16 oz equal 7,680 gr.

  • How many grains are in 2 lb? You know that 7,680 gr are in 1 lb; therefore, 15,360 gr are in 2 lb. (See Measure for measure.)