Lesson 4-6Mastering Volume Conversions

Volume is the measure of the amount of space an object or substance occupies. A grain of sand has a minuscule volume compared with the Rock of Gibraltar; nevertheless, the lowly grain of sand has a measurable volume. Solids, liquids, and gasses that are confined to some sort of container, all occupy space and can be measured in terms of their volume.

 In the healthcare profession--especially when talking about medications--the term volume refers to liquid measurements.

Units of Measure for Liquid Volume
 Metric US Standard Apothecary microliter milliliter liter mcm ml L fluid ounce pint quart gallon fl. oz pt qt gal grain gr

 NOTES: You will occasionally see liquid volume expressed in units of cubic centimeters (cc). This isn't a cause for concern, however, because 1 cc is the same as 1 ml. As a health professional, you won't work with microliters (mcm) very often. Science and technology professions prefer the label mL. The US Standard ounce is properly called a fluid ounce (fl. oz) to distinguish it from the weight/mass version where 16 ounces (oz) equals one pound (lb).

 Most Common Conversion Factors for Liquid Volume Metric US Standard System Conversion 1,000,000 mcm per L 1000 ml per L 16 fl.oz per pt2 pt per  qt 4 qt per gal 1 qt = 0.946 L

Volume Conversion Map

Metric Volume Conversions

Metric volume conversions are relatively easy because the conversion factors are all multiples of 10.  In fact, there is only one purely metric volume conversion:  milliliters to liters and vice-versa.

 1000 ml per 1 Lor1 L per 1000 ml

 Note: The cubic centimeter (cc) measurement is still used today, but you should easily remember that 1 cc is equivalent to 1 ml.

Example 1: Converting Milliliters to Liters

Convert 1250 ml to L

Given Volume:  1250 ml
Conversion Factor:  1 L per 1000 ml

Set up the ratios:
 1250 ml x 1 L 1 1000 ml
Cancel the labels:
 1250 x 1 L 1 1000
Complete the math:
 1250 x 1 L = 1.25 L 1 1000
Result: 1.25 L

Example 2: Converting Liters to Milliliters

Convert 0.055 L to ml

 0.055 L x 1000 ml 1 1 L
 0.055 x 1000 ml 1 1
 0.055 x 1000 ml = 55 ml 1 1

0.055 L = 55 ml

 Note Notice how you don't have to figure out whether your are supposed to multiply or divide. You simply take the proper conversion factor ( 1000 ml per 1 L, in these examples) and arrange it so the unwanted labels cancel out.  In Example 1, you want to get rid of the ml label, so you flip over the conversion ratio so that the ml label is on the bottom. In Example 2, you want to get rid of the L label, so you flip over the same conversion factor so that L labels cancel.

Examples 3: Converting Between Liters and Cubic Centimeters

3-1. Convert 0.15 L to cc.

 0.15 x 1000 cc = 150 cc 1 1

3-2  1280 cc = _____ L

 1280 x 1 L = 1.28 L 1 1000

Metric Volume Drill

 Work with this drill routine until you can consistently make the conversions correctly. Click the Answer button to see the correct answer to the question. Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

US Volume Conversions

The US Standard volume measurements most commonly encountered in the healthcare professions are:

 16 fl.oz per pt or 1 pt per 16 fl.oz 2 pt per 1 qt or 1 qt per 2 pt 4 qt per 1 gal or 1 gal per 4 qt

Example 4: Converting Fluid Ounces to Pints

Convert 18 fl. oz to pt

Given Volume:  18 fl. oz
Conversion Factor:  1 pt per 16 fl. oz

Set up the ratios:
 18 fl. oz x 1 pt 1 16 fl. oz
Cancel the labels:
 18 x 1 pt 1 16
Complete the math:
 18 x 1 pt = 1.13 pt 1 16
Result: 1.13 pt

Examples 5: Converting US Volume Measurements

5-1. Convert 0.1 pint to units of fluid ounces.

 0.1 x 16 fl. oz = 1.6 fl. oz 1 1

5-2. Convert 10 pt to qt.

 10 x 1 qt = 5 qt 1 2

5-3. Convert 0.1 gallon to quarts.

 0.1 x 4 qt = 0.4 qt 1 1

Sometimes you have to use multiple conversion ratios, rather that looking up conversion factors you haven't memorized.

5-4. Convert 1600 fluid ounces to gallons.

US Standard Volume Drill

 Work with this drill routine until you can consistently make the conversions correctly.Click the Answer button to see the correct answer to the question.Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

Metric/US Volume Conversions

It is possible to make up all sort of metric-to-US and US-to-metric volume conversions, but there is just one that stands out from the rest: converting between cc (or ml) and fluid ounces. In fact, if you memorize this conversion ratio you will be able to use multiple conversion ratios to work out any other metric/US volume conversion without having to memorize or look up their ratios.

 1 fl. oz per 29.6 ml or 29.6 ml per fl. oz

Note

Recall that 1 cc = 1 ml, so you can also put the ratio this way:

 1 fl. oz per 29.6 cc or 29.6 cc per fl. oz

Example 6: Converting Fluid Ounces to Cubic Centimeters

Convert 3/4 fl. oz to cc

Given Volume:  0.75 fl. oz
Conversion Factor:  29.6 cc per fl. oz

Set up the ratios:
 0.75 fl. oz x 29.6 cc 1 1 fl. oz
Cancel the labels:
 0.75 x 29.6 cc 1 1
Complete the math:
 0.75 x 29.6 cc = 22.2 cc 1 1
Result: 22.2 cc

Examples 7: Converting Between Metric and US Volume Measurements

7-1. 100 ml = _____ fl. oz

 100 x 1 fl. oz = 3.4 fl. oz 1 29.6

7-2. 1 L = _____ fl. oz

The conversion ratio for liters and fluid ounces is not ordinarily provided on conversion charts. So it is necessary to convert the liter to another unit that is normally associated with fluid ounces ... and that would be ml.  You should know by now that 1 L = 1000 ml, so substitute that ratio:

So instead of trying to work with liters

 1 x 1 fl. oz = 1 ???

work with the equivalent number of ml--a conversion ratio that is more commonly known:

 1000 x 1 fl. oz = 33.8 fl. oz 1 29.6

Answer: 1 L = 33.8 fl. oz

Fluid Ounces and Cubic Centimeter Drill

 Work with this drill routine until you can consistently make the conversions correctly.Click the Answer button to see the correct answer to the question.Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

Household  Volume Measurements

The household volume measurements you are likely to encounter as a health worker are cup (c) , teaspoon (tsp or t), and tablespoon (tbs or T). Here are the conversion ratios:
 5 ml per 1 tsp or 1 tsp per 5 ml 3 tsp per 1 tbs or 1 tbs per 3 tsp 8 fl. oz per c or 1 c per 8 fl. oz

Also remember that units of ml and cc are identical.

Examples 8: Converting Household Volume Measurements

8-1.  The instructions on a bottle of cough medicine call for taking 2 tsp every six hours. How much is each dose in ml?

8-2. How many cubic centimeters in one cup?

Recall that 1 fl. oz = 29.6 cc

8-3. 1 tbs = _____ ml

Household Measurements Drill

 Work with this drill routine until you can consistently make the conversions correctly.Click the Answer button to see the correct answer to the question.Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

Topic Summary: Volume Conversions

Volume Conversions Drill

 Work with this drill routine until you can consistently make the conversions correctly.Click the Answer button to see the correct answer to the question.Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

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 Lesson 4-7Mastering Mass/Weight Conversions

 Metric US Standard Apothecary microgram milligram gram kilogram mcg mg g kg ounce pound ton oz lb T grain gr

 Note The label for micrograms (mcg) is used primarily in medicine and pharmacy. It is written as mg in most technical trades and science professions.

Mass (Weight) Conversion Map

Metric Mass Conversions

 1000 mcg per 1 mg or 1 mg per 1000 mcg 1000 mg per 1 g or 1 g per 1000 mg 1000 g per 1 kg or 1 kg per 1000 g

Example 1: Converting Micrograms to Milligrams

Convert 3500 micrograms to milligrams.

 Given Mass:  3500 mcg Conversion Factor:  1000 mcg per 1 mg Set up the ratios: Cancel the labels: Complete the math: Result: 3.5 mg

Examples 2: Converting Metric Mass

2-1. Convert 0.02 gm to milligrams.

2-2. Express 5 mg in micrograms.

Volume Conversions Drill

 Work with this drill routine until you can consistently make the conversions correctly.Click the Answer button to see the correct answer to the question.Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

US Standard Mass (Weight) Conversions

 16 oz per 1 lb or 1 lb per 16 oz 2000 lb per 1 T or 1 T per 2000 lb

Example 3. Converting Pounds to Ounces

Convert 35 oz to pounds

 Given Mass:  35 oz Conversion Factor:  1 lb per 16 oz Set up the ratios: Cancel the labels: Complete the math: Result: 2.19 lb

Mass Conversions Drill

 Work with this drill routine until you can consistently make the conversions correctly.Click the Answer button to see the correct answer to the question.Click the Next button to see the next question. Your browser does not support inline frames or is currently configured not to display inline frames.

Mixed-Standard Mass Conversions

 1 gr per 60 mg or 60 mg per 1 gr

Examples x: Converting Grains

How many grains in one ounce?

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 Lesson 4-8Mastering Time and Rate Conversions

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