Direct Proportion Definition

By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on September 11, 2018

Definition: Direct proportion is the relationship between two variables when their ratio is equal to a constant value.

Examples:

  • The volume of an ideal gas is directly proportional to the absolute temperature of the gas (Charles' Law)
  • If you get paid by the hour, the more you work the more you will get paid. If you earn $15/hour and work 2 hours, you will earn $30 (Not including taxes, etc.) and if you work 4 hours, you will earn $60. The ratio of money earned to hours worked is 15 to 1 or $15/hour.
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Helmenstine, Anne Marie, Ph.D. "Direct Proportion Definition." ThoughtCo, Jan. 29, 2020, thoughtco.com/definition-of-direct-proportion-605034. Helmenstine, Anne Marie, Ph.D. (2020, January 29). Direct Proportion Definition. Retrieved from https://www.thoughtco.com/definition-of-direct-proportion-605034 Helmenstine, Anne Marie, Ph.D. "Direct Proportion Definition." ThoughtCo. https://www.thoughtco.com/definition-of-direct-proportion-605034 (accessed June 5, 2023).