# Apothecary/metric equivalents

## Abbreviations

Selected abbreviations are listed below.

Abbreviation Unit of measurement
g gram
gal. gallon
gr grain
kg kilogram
lb pound
M or min minim
mcg microgram
mg milligram
mL milliliter
oz ounce
pt pint
qt quart
tbsp tablespoon
tsp teaspoon

Other common abbreviations used in the medical field:

Abbreviation Meaning
a.a. of each
a.c before meals
b.i.d. twice a day
c. with
gtt. drop, drops
h.s. at bedtime
o.d. right eye
o.s. left eye
p.c. after meals
p.r.n. as needed
q.i.d. four times a day
t.i.d. three times a day
u.d. as directed

## Approximate Liquid Measures

1 fluid ounce = 30 milliliters

One liter of pure water weighs approximately one kilogram so 1cc (mL) of water weighs 1 gram.

"A spoonful" generally means heaped or rounded, with as much above the bowl of the spoon as in the spoon. However, a measure of liquid is a level spoonful.

Apothecary measurement Metric equivalent
1 gallon 3800 mL
1 gallon 128 fluid oz
1 quart 960 mL
1 quart 32 fluid oz
1 pint 480 mL
1 pint 16 fluid oz
4 fluid oz 120 mL
8 fluid oz 240 mL
10 minims 0.6 mL
15 minims 1 mL

## Approximate Household Equivalents

1 teaspoonful = 5 milliliters

1 tablespoonful = 15 milliliters

1 ounce = 30 grams

1 gram = 15 grains

Apothecary measurement Metric equivalent
2 oz 60 g
4 oz 120g
16 oz 1 lb
1/200 gr 300 mcg
1/150 gr 400 mcg
1/100 gr 600 mcg
1gr 60 mg
7 ½ gr 500 mg
10 gr 600 mg

## Metric Conversions

In 1866, the United Stated Congress legalized the use of the metric system within the United States. The law also established approximate equivalents between customary and metric measurements.

1 gram = 1,000 milligrams

1 milligram = 1,000 micrograms

Apothecary measurement Metric equivalent
0.05 mg 50 mcg
0.5 mg 500 mcg
5 mg 5,000 mcg
0.05 g 50 mg
0.5 g 500 mg
5 g 5,000 mg