Length

• 1). Convert the distance from whatever U.S. unit it is written in into feet, before converting into metric units. For example, one yard converts to three feet. One inch converts to 1/12 feet. One mile converts to 5,280 feet.
  
  
• 2). Convert the number of feet into meters by multiplying it by 0.3048.
  
  
• 3). Convert the number of meters to an appropriate unit for the scale of the distance. For example, 1,000 meters converts to 1 kilometer, and 1/1,000 of a meter converts to a millimeter.
  
  

Volume

• 1). Convert the volume from whatever U.S. unit it is written in into gallons before converting into metric units. For example, one fluid ounce equals 0.0078125 gallons, and one cup equals 0.0625 gallons.
  
  
• 2). Convert the number of gallons to liters by multiplying by 3.7854. The result is the number of liters.
  
  
• 3). Convert the number of liters to an appropriate unit for the scale of the volume. For example, 1/1,000 of a liter equals a milliliter.
  
  

Temperature

• 1). Subtract 32 from the number of degrees Fahrenheit of temperature.
  
  
• 2). Multiply by 5.
  
  
• 3). Divide by 9. The result is the temperature in degrees Celsius.