The Kardashev Scale: Classifying Extraterrestrial Civilizations


Recently, there have been reports of alien sightings that are unexplainable, but how could we categorize and identify alien civilizations?

The Kardashev Scale was created in 1964 by Nikolai Kardashev, a Soviet astrophysicist, in his paper titled “Transmission of Information by Extraterrestrial Civilizations” as a way to categorize potential alien civilizations.

He proposed that each type of civilization should be categorized by the amount of energy they could utilize. The beauty of this system is its simplicity. Energy, the capability to do work, is a universal force that we can assume any civilization would require in order to advance.

In his original article, Kardashev proposed three types of civilizations:

  • Type I civilizations possess the ability to utilize all the energy of a planet
  • Type II civilizations possess the ability to utilize all the energy of a solar system
  • Type III civilizations possess the ability to utilize all the energy of a galaxy

Extensions and alternatives to the Kardashev Scale

As you can see, humans wouldn’t even be on this scale, which is why extensions have been suggested. The extensions that are seen most commonly are a Type 0 civilization that does not possess the ability to utilize any significant amount of energy, a Type IV civilization that can use the energy of multiple galaxies, or even the entire universe.

Some of these extensions can feel a bit ridiculous, and the Kardashev Scale has come under criticism for being too speculative. If we can’t understand alien civilizations, how could we predict how they would develop? While this is true, it is crucial to understand the Kardashev Scale has given us a concrete way to analyze alien civilizations, and how the scale has opened new discussions around the topic.

Another addition to the scale, and perhaps the most useful, was Carl Sagan’s defining intermediate values by extrapolating the value of energy for each type and putting it on a logarithmic scale.

Where are we?

With Carl Sagan’s variation of the Kardashev Scale, we can categorize our own. In 2019, the world consumed 173,340 TWh (around 1.9 x 1013 Watts), placing humanity at approximately 0.75 on the Kardashev Scale. It is estimated by some astrophysicists that within 200 years, we will achieve a Type I civilization. It may be a while before humanity becomes a Type II civilization. The difference between Type I and II civilizations is a factor of 10 billion.

The Kardashev Scale provides humanity with a roadmap for the future, as well as a goal to strive for. It may very well be leading us to the next step in human development.


Cirkovic, Milan M. “Kardashev’s Classification at 50+: A Fine Vehicle with Room for Improvement.”, 7 Jan. 2016,

Kaku, Michio. “Who Will Inherit the Universe?” Astronomy, vol. 30, no. 2, 02, 2002, pp. 34-38. ProQuest,

Kardashev, Nikolai. “1964SvA…..8..217K Page 217.” Transmission of Information by Extraterrestrial Civilizations,…..8..217K.

Last, Cadell. “Big Historical Foundations for Deep Future Speculations: Cosmic Evolution, Atechnogenesis, and Technocultural Civilization.” Foundations of Science, vol. 22, no. 1, 2017, p. 39+. Gale OneFile: Science, Accessed 12 May 2021.

Lovell, Christopher. “Classifying Civilisations: An Introduction to the Kardashev Scale.” Astrobites, 15 Mar. 2016,

Ritchie, Hannah. “Energy Mix.” Our World in Data,
Tmurphy, et al. Do the Math, 12 July 2011,

Ward, Jacob. “Powerful Ambitions.” Popular Science, vol. 282, no. 6, 06, 2013, pp. 6. ProQuest,