Some fields of engineering in the United States use a system of measurement of physical quantities known as the English Engineering units.[1][2] The system is based on English units of measure.


The English Engineering units is a set of consistent units used in the United States. The set is defined by the following units,[3] with a comparison to the standard units based on the International System of Units.[4]

Dimension English Engineering unit SI unit
time second (s) second (s)
length foot (ft) meter (m)
mass pound mass (lb) kilogram (kg)
force pound force (lbf) newton (N)
temperature degree Fahrenheit (°F) degree Celsius (°C)
absolute temperature degree Rankine (°R) kelvin (K)

Units for other physical quantities are derived from this set as needed.

In English Engineering units, the pound mass and the pound force are distinct base units, and Newton's Second Law of Motion takes the form F = ma/gc, where gc = 32.174 lb·ft/(lbf·s2).

A similar system is termed British engineering units by Halliday and Resnick, a system that uses the slug as the unit of mass, but in which Newton's law retains the form F = ma.[5]

See also


  1. ^ Comings, E. W. (1940). "English Engineering Units and Their Dimensions". Ind. Eng. Chem. 32 (7): 984–987. doi:10.1021/ie50367a028. 
  2. ^ Klinkenberg, Adrian (1969). "The American Engineering System of Units and Its Dimensional Constant gc". Ind. Eng. Chem. 61 (4): 53–59. doi:10.1021/ie50712a010. 
  3. ^ R. Zucker, O. Biblarz (2002). Fundamentals of Gas Dynamics. Hoboken, New Jersey: John Wiley & Sons, Inc. ISBN 0-471-05967-6. 
  4. ^ International Bureau of Weights and Measures (2006), The International System of Units (SI) (PDF) (8th ed.), ISBN 92-822-2213-6, archived (PDF) from the original on 2017-08-14 
  5. ^ Halliday, David; Resnick, Robert (1974). Fundamentals of Physics (revised printing ed.). New York: Wiley. pp. 35, 68–69.