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Medicine LibreTexts

1.5: Units of Measure

  • Page ID
  • Learning Objectives

    • Compare and contrast the Metric and US Customary systems of measurement.

    In nutrition, there are two systems of commonly used measurements: Metric and US Customary. The US Customary system is more commonly used among the public in the United States.  For example, many people refer to body weight in pounds, rather than in kilograms.  However, the Metric system is more commonly used in science.  It is good to become familiar with both measurements, and to learn how to convert between them.

    The Metric and US Customary System

    These are commonly used prefixes for the Metric System:

    Micro- (μ) 1/1,000,000th (one millionth)
    Milli- (m) 1/1000th (one thousandth)
    Centi- (c) 1/100th (one hundredth)
    Deci- (d) 1/10th (one tenth)
    Kilo- (k) 1000x (one thousand times)


    Metric System US Customary System Conversions
    Microgram (μg) Ounce (oz) 1 oz = 28.35 g
    Milligram (mg) Pound (lb) 1 lb = 16 oz
    Gram (g)   1 lb = 454 g
    Kilogram (kg)   1 kg = 2.2 lbs


    Metric System US Customary System Conversions
    Milliliter (mL) Teaspoon (tsp) 1 tsp = 5 mL
    Deciliter (dL) Tablespoon (tbsp) 1 tbsp = 3 tsp = 15 mL
    Liter (L) Fluid ounce (fl oz) 1 fl oz = 2 tbsp = 30 mL
      Cup (c) 1 c = 8 fl oz = 237 mL
      Pint (pt) 1 pt = 2 c = 16 fl oz
      Quart (qt) 1 qt = 4 c = 32 fl oz = 0.95 L
      Gallon (gal) = 4 qt 1 gal = 4 qt


    Metric System US Customary System Conversions
    Millimeter (mm) Inch (in) 1 in = 25.4 mm
    Centimeter (cm) Foot (ft) 1 ft= 30.5 cm
    Meter (m) Yard (yd) 1 yd = 0.9 m
    Kilometer (km) Mile (mi) 1 mi = 1.6 km


    Video \(\PageIndex{1}\): Math Antics - Intro to the Metric System.  Available at



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