What Is the Kardashev Scale?
The Kardashev scale ranks civilizations by the energy they command, from a planet’s worth to a star’s to a galaxy’s, and by its measure humanity has not yet reached the first rung.
In 1964, the Soviet radio astronomer Nikolai Kardashev asked a practical question: how powerful would a civilization have to be for us to hear it across interstellar space? His answer sorted civilizations into three types by the energy they use. A Type I civilization uses roughly the energy humanity used in the 1960s. A Type II uses the full output of its star. A Type III uses the energy of an entire galaxy. Each step is a leap of more than a hundred billion times.
In 1973, Carl Sagan turned the three types into a sliding scale, so a civilization could score 0.7 or 1.4. Humanity used a little over 600 exajoules of energy in 2025, which puts us at about 0.73. We are not yet a Type I civilization, as Sagan defined it.
The scale gives astronomers something to look for. A civilization capturing most of its star’s light would glow with waste heat in the infrared, and searches of hundreds of thousands of galaxies and millions of stars have looked for that glow. So far, every candidate has had a natural explanation or remains unconfirmed. That silence is part of the Fermi paradox, and it is why the scale matters to the disclosure question.
Sources: N.S. Kardashev, “Transmission of Information by Extraterrestrial Civilizations,” Soviet Astronomy (1964) · Carl Sagan, The Cosmic Connection (1973) · Energy Institute, Statistical Review of World Energy (2026)
Either they don’t exist, or they don’t yet use enough energy for us to recognize them.
The Three Types
Kardashev defined each type by power, the energy used per second. The numbers are so large that each type is a different kind of civilization, not just a bigger one.
Type I: a planet’s energy. About 4 × 10¹² watts in Kardashev’s original paper, roughly what Earth’s civilization used in 1964. Later writers often redefine Type I as all the energy a planet receives from its star, about 10¹⁶ to 10¹⁷ watts, which is the definition Sagan’s scale uses and the reason humanity scores below 1.
Type II: a star’s energy. About 4 × 10²⁶ watts, the entire output of the Sun. The physicist Freeman Dyson suggested in 1960 that a civilization might do this by surrounding its star with solar collectors, now called a Dyson sphere.
Type III: a galaxy’s energy. About 4 × 10³⁷ watts, comparable to all the stars of the Milky Way.
Beyond Type III. Types IV and V, for civilizations harnessing energy beyond a galaxy, come from later writers such as John Barrow and Michio Kaku. Kardashev did not define them.
Sources: Kardashev (1964) · Freeman J. Dyson, “Search for Artificial Stellar Sources of Infrared Radiation,” Science (1960) · Sagan (1973)
Where Humanity Stands
On Sagan’s sliding scale, every tenfold increase in power adds a tenth of a point.
Sagan’s formula is K = (log₁₀ P − 6) / 10, where P is power in watts. Global energy use of about 600 exajoules a year works out to roughly 19 trillion watts, or K ≈ 0.73. Reaching Type I would mean using about 500 times more energy than we do now.
Sagan thought energy alone was too crude a measure. He proposed a second scale for the information a civilization holds, graded by letters from A to Z, and rated humanity low on it as well.
Sources: Sagan (1973) · Energy Institute, Statistical Review of World Energy (2026)
Looking for Type II and Type III
Energy can’t be hidden. Whatever a civilization uses, it eventually sheds as heat, and that heat is what astronomers search for.
In 2015, a Penn State team led by Roger Griffith and Jason Wright searched about 100,000 galaxies in data from NASA’s WISE infrared telescope for the glow of a galaxy-spanning civilization. About 50 galaxies showed unusual infrared emission worth a closer look, but none showed a clear sign of one. In 2024, Project Hephaistos sifted about five million objects and reported seven stars with puzzling infrared excess. A follow-up analysis that year suggested they may be distant dust-shrouded galaxies lined up behind ordinary stars.
The best-known false alarm was Tabby’s Star (KIC 8462852), whose strange dimming in 2015 led some astronomers to raise the possibility of a megastructure. Later observations pointed to dust.
Sources: Griffith et al., Astrophysical Journal Supplement Series (2015) · Suazo et al., Monthly Notices of the Royal Astronomical Society (2024) · Andrew W. Blain (2024)
Why It Matters for Disclosure
The scale measures how far ahead another civilization could be. That distance is what makes contact a civilizational question, not just a scientific one.
If there are advanced civilizations, the scale says we should expect many of them to be far ahead of us, because a civilization only a few thousand years older could have climbed a long way. The Fermi paradox asks why none of them have been seen. The disclosure movement asks a related question: whether some of what has been seen, and kept from the public, already answers it.
For the New Paradigm Institute, that is why preparation matters. A humanity at 0.73 would be meeting whoever is out there from a very low rung. How well we meet them may depend less on our energy than on what Sagan’s second scale measures: what we know, and whether we have been told the truth.
Citizens for Disclosure
Citizens for Disclosure is NPI’s volunteer network: local and state chapters across the country, citizens lobbying their own representatives, and an Interfaith Global Alliance for Disclosure that CfD is building. It’s free to join, no donation required, and our team will help you find your place in it.
Related
- What Is the Fermi Paradox? · Core Learning Tool
- Could Disclosure Re-Enchant the Universe? · Full Disclosure, episode 18
- The UAP Disclosure Timeline · Core Learning Tool
