Astrobiology
Drake Equation
How many alien worlds exist with which we can communicate?
What are our chances of communicating with intelligent aliens? Are there other habitable worlds in our galaxy? Is there life elsewhere in our galaxy? Is there intelligent life? Are there other technological civilizations in our galaxy with whom we can communicate? How can we estimate how many there are of each of these?

In 1961, Dr. Frank Drake developed the Drake Equation to estimate the number of other technological civilizations that exist in our galaxy with whom we can communicate. Use the adapted version below to calculate the number of worlds within our Milky Way Galaxy that have intelligent life whose radio emissions should be detectable.

Enter your estimates for each term below. You can learn more about each term and receive some help deciding upon estimated values by clicking on the links. When you are done, click on the calculate button.

Term A:
number of stars in
the Milky Way Galaxy
 
*select a magnitude for this number 		X  Term B:
percent of these stars
that are appropriate
%
X  Term C:
percent of appropriate
stars that have
planetary systems
% 		X  Term D:
average number of
habitable planets
within a system
X  Term E:
percent of habitable
planets that have life
% 		X  Term F:
percent of planets
with life that
develop intelligent life
%
X  Term G:
percent of intelligent life
with radio technology
% 		X  Term H:
percent of those radio
technologies that are "current"
%
= number of worlds in our Milky Way Galaxy
with intelligent life whose radio emissions
should be detectable
 

Note: for calculations, percentages are treated as decimals, e.g. 20% = 0.2

Also based on your numbers, you have calculated that there are:
habitable planets in the Milky Way Galaxy
planets in the Milky Way with life
planets in the Milky Way with intelligent life