System of Measurements
Three main systems of measurements are used by healthcare professionals: household measurement system, apothecary measurement system, and metric system of measurement. It is important to be able to work within each system and to convert between the systems when working with medication dosages. In order to do this, you must first have an understanding of what each system is and what measurements are within each.
Household Measurement SystemHousehold measurement system, also called the U.S. Customary Measurement, is commonly used in cookbooks and recipes. This system uses whole numbers and fractions. It is also considered the least accurate measurement system because of the differences between the measuring devices.
As patient care moves away from hospitals and back into the community, it will be necessary for healthcare providers to understand this measurement system. You may need to use this system to provide teaching for a home care patient. In order to do this, you must learn and memorize the common household equivalencies and their abbreviations to convert within the system.
Household Measurement System Equivalencies |
Unit |
Abbreviation |
Equivalent |
Weight |
||
Ounce | oz | - |
Pound | lb, # | 16 oz |
Liquid Volume | ||
Gallon | gal | 4qt, 8pt, 16c, 128fl.oz |
Quart | qt | 2pt, 4c, 32fl.oz |
Pint | pt | 2c, 16fl.oz |
Cup | c | 8fl.oz |
Ounce | fl. oz | 2Tbsp, 6tsp |
Tablespoon | T, Tbsp | 3tsp |
Teaspoon | t, tsp | 75gtt |
Drop | gtt | - |
The correct format to use when writing this measurement system is: number and unit. For example, ¼ cup or ½ Tbsp.