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There are three forms of measures, metric, apothecary and household used in nursing.  This lesson will introduce you to these measures.

 

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Metric Weight Measures

Metric Volume Measures

Metric Length Measures

Apothecaries Measures

Household Measures

Metric to Apothecary Conversion

Metric to Household Conversion

Apothecaries to Household Conversion

 


The metric system of measurement is the most widely used system of measurement in the world.  It is the preferred system for administering medications, because it is based on a series of 10 measures or multiples of 10.  It is a simple and accurate form of measurement between health care professionals. 

 

Metric Weight Measures

1 kilogram (kg, Kg) = 1000 grams or 1000 g
1 gram = 1000 milligrams or 1000 mg
1 milligram (mg) = 1000 micrograms or 1000 mcg
1 microgram (mcg) =  0.001 milligrams or 0.001 mg

1 milligram = 0.001 gram or 0.001 g
1 microgram (mcg) = 0.000001 gram or 0.000001 g

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Metric Volume Measures

1 milliliter (ml) = 0.001 liter or 0.001 L
1 liter = 1000 milliliters or 1000 ml
1kiloliter = 1000 liters or 1000 L

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Metric Length Measures
1 millimeter (mm) =  0.001 meter
1 centimeter (cm) = 0.01 meter or 0.01 m
1 decimeter (dm) = 0.1 meter or 0.1 m
1 kilometer (km) = 1000 meters or 1000 m
1 meter (m) = 100 centimeters or 100 cm
1 meter (m) = 1000 millimeters or 1000 mm

1 centimeter (cm) = 10 millimeters or 10 mm
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The apothecaries system of measurement is the oldest system of drug measurement.  In fact, it was the first system used to measure medication amounts. It is infrequently used as a drug measurement. There are a few medications that are still measured in grains (gr). To ensure administration of the correct dose of medication to a patient, it is important to know the conversion of grains to milligrams and how to convert from one system of measurement to another.


Apothecaries measures

60 grains (gr) = 1 dram

8 drams = 1 ounce or 1 oz.

1 fluid dram = 60 minims
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The household system of  measurement is based on the apothecary system of measures. Household measures are used to measure liquid medications.  Parents understand one teaspoon of liquid medication more clearly than ordering 15 milliliters.  The important thing to realize with household measures is that these measures are not as exact as the metric system of measurement.  Also the comparison of metric measures to household measures are not equal.  These measures are called equivalent measures because the measurement is close enough.  A liter is very close in equal measurement to a quart.  It is not an exact measure. It is an equivalent. 

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Household measures

3 teaspoons (tsp) = 1 tablespoon or 1 tbsp
1 ounce (oz) = 2 tablespoons or 2 tbsp
1 pint (pt) = 2 cups or 2 c
1 pint (pt) = 16 ounces or 16 oz
1 juice glass  = 4 ounces or 4 oz
1 coffee cup = Usually 6 ounces or 6 oz, but can vary depending on size of cup.
1 glass = 8 ounces or 8 oz
1 measuring cup (c) = 8 ounces or 8 oz
1 teaspoon (tsp) = 60 drops or 60 gtt
1 quart (qt) = 2 pints or 2 pt
1 gallon (gal)= 4 quarts or 4 qt
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Metric to Apothecary Conversion

1 gram (gm) = 15 grains or 15 gr
15 (16) grains (gr) = 1000 milligram or 1000 mg
7.5 grains (gr) = 500 milligrams or 500 mg
5 grains (gr) = 300 (325) milligrams or 300 (325) mg
1.5 grains (gr) = 100 milligrams or 100 mg
1 grain (gr) = 60 milligrams or 60 mg
A half (0.5) grain (gr) = 30 milligrams or 30 mg
0.6 milligrams (mg) = 1/100 grain or 1/100 gr
0.4 milligrams = 1/150 grain or 1/150 gr
0.3 milligrams (mg) = 1/200 grain or 1/200 gr
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Metric to Household Conversion

1 kilogram (kg) = 2.2 pounds or 2.2 lb
1000 grams (gm) = 2.2 pounds or 2.2 lb
30 milliters or 30 ml = 1 ounce (oz)
1 liter (L) is equivalent to 1 quart or 1 qt
500 milliters or 500 ml = 1 pint (pt)
240 milliters or 240 ml = 1 glass
180 milliters or 180 ml = 1 teacup
15 milliters or 15 ml = 1 tablespoon (T)
5 milliters or 15 ml = 1 teaspoon (t)
1 milliter (ml) =  15 - 16 drops or 15 - 16 gtts
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Apothecaries to Household Conversions

32 fluid ounces = 1 quart (qt)
16 fluid ounces = 1 pint (pt)
480 grains or 480 gr = 1 ounce (oz)
1 minim = 1 drop or 1 gtt
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These measures should be memorized to assist with medication calculation problems.  It may be necessary to convert from one measure to another before you can begin to solve medication problem.  The learning activity utilizes flash cards to help you memorize these facts. 

 

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