The gallon, quart, pint, and fluid ounce of the apothecary system are the familiar

units used in the United States to measure liquids such as milk, gasoline, and soft

drinks. Table 1-8 provides some useful information on commonly encountered

apothecary volume units.

1 gallon (C. or gal.) =

4 quarts =

8 pints

1 quart (qt.)

=

2 pints

=

32 fluid ounces

)

1 pint (pt.)

=

16 fluid ounces (fl. oz. or

Table 1-8. Commonly encountered apothecary volume units.

a. To convert quantities from one system of measurement to another, a familiar

tool, ratio and proportion, can be used. Table 1-9 contains some useful approximate

conversion factors. Remember, the conversion factors are approximate. When the

exact conversion factors are required (that is, when prescriptions are compounded),

pharmaceutical texts or references should be consulted.

Weight

2.2 pounds

=

1 kilogram (kg.)

1 grain (gr.)

=

60 milligrams (mg.)

Fluid Measure

1 fluid ounce (fl. oz.,

)

=

30 milliliters

1 pint

=

473 milliliters

Table 1-9. Approximate conversion factors.

b. The process of converting from one system to another can be done with ease

if three steps are followed:

(1) Write the conversion factor as your **IF **ratio.

(2) Write the unknown factor as your **THEN **ratio.

(3) Solve for the unknown as in any ratio and proportion problem.

MD0913

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