Drake Equation Calculator

• Choose Scenario: You can choose between three preset scenarios or enter your own values. Conservative uses lower assumptions for life, intelligence and detectable lifetime, Illustrative uses more moderate example values, and Optimistic assumes that technological civilizations are more common or remain detectable for much longer.

• Adjust the Factors: You can change all seven values of the Drake Equation yourself at any time and immediately see how strongly each assumption affects the result.

  • R* - Star Formation Rate: Indicates how many suitable new stars are formed in the Milky Way on average per year. 

  • fp - Stars With Planets: Indicates what percentage of suitable stars have planetary systems. 

  • ne - Potentially Habitable Worlds: Indicates the average number of potentially habitable planets per planetary system.

  • fl - Life Develops: Indicates what percentage of potentially habitable worlds actually develop life.

  • fi - Intelligent Life: Indicates what percentage of life-bearing worlds eventually develop intelligent life.

  • fc - Detectable Technology: Indicates what percentage of intelligent civilizations develop technologies that could make their existence detectable over large distances. 

  • L - Detectable Lifetime: Indicates how many years a technological civilization remains detectable on average. This does not necessarily mean its entire lifespan, but rather the period during which it produces signals or other technosignatures that could potentially be detected. 

• Calculate: Once you are happy with your values, click Calculate to calculate N.

• N - Estimated Detectable Civilizations: N is the result of the Drake Equation and represents the estimated number of technological civilizations in the Milky Way that could be detectable at the same time under the assumptions you have chosen.

Origin of the Drake Equation

Frank Drake developed the equation in 1961 in connection with the search for extraterrestrial radio signals. Instead of simply asking how many extraterrestrial civilizations might exist, the Drake Equation breaks that question down into several smaller factors.

The classic equation is:
N = R* × fp × ne × fl × fi × fc × L

Multiply all seven factors together and you get N, the estimated number of technological civilizations in the Milky Way that could be detectable at the same time.

The Drake Equation was never intended as a way to calculate the exact number of extraterrestrial civilizations. Its real value lies in making the many different conditions visible that have to fall into place between the formation of a star and the emergence of a detectable technological civilization.

Why Can the Results Be So Different?

The interesting thing about the Drake Equation is also its biggest problem: We simply do not know the correct values for several of its factors.

Some of them can be estimated much better today than Frank Drake could in 1961. We now know, for example, that planets around other stars are very common.

For other factors, however, we still have practically no idea. We do not know how likely it is for life to actually emerge on a suitable planet. We know even less about how often intelligent life develops from it, how often it goes on to develop detectable technology, or how long a technological civilization remains detectable on average.

That means different assumptions can lead to completely different results. Depending on the values you enter, the Drake Equation can produce a large number of possible civilizations or a result that is practically zero.

What Does the Result Actually Mean?

The result of the calculator is not a prediction of how many extraterrestrial civilizations actually exist.

Because all seven factors are multiplied together, even a single very small value can dramatically change the final result. If you assume, for example, that life emerges frequently but intelligent life develops on only a tiny fraction of those worlds, N can still become very small.

The factor L can also have an especially large impact. If technological civilizations remain detectable for only a few hundred years, the result becomes much smaller. If they remain detectable for hundreds of thousands or even millions of years, N can increase enormously.

Depending on the assumptions you make, the equation can give you a Milky Way with many possible technological civilizations or one in which we might actually be pretty much alone.

Which of those comes closest to reality? We don't know.