Calculate drake equation

Explore an estimated number of detectable communicating societies from seven uncertain factors.

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ToolDrake Equation Calculator
Input
Output
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How it works

The product multiplies star-formation rate, planet fraction, habitable planets per star, life fraction, intelligence fraction, communication fraction, and communicating lifetime. It is an expectation under supplied assumptions, not a measured census.

  • Every factor is supplied because biological and longevity terms are uncertain.
  • Four significant digits keep the result readable as an order-of-magnitude exercise.

Worked example

Drake's original 1961 guesses
The values used at the Green Bank meeting where the equation was first presented
Input
											Star formation rate per year: 1
Fraction with planets: 0.2
Habitable planets per star: 1
Fraction developing life: 1
Fraction developing intelligence: 0.01
Fraction developing communication: 0.01
Communicating lifetime years: 10000
Output
												Estimated civilisations: 0.2
Star formation rate per year: 1
Fraction with planets: 0.2
Habitable planets per star: 1
Fraction developing life: 1
Fraction developing intelligence: 0.01
Fraction developing communication: 0.01
Communicating lifetime years: 10000

When to use this

SETI discussions vary society counts, astrobiology classes examine compounded assumptions, and Fermi-paradox exercises change lifetime and detectability.

Edge cases

  • A zero fraction makes the product zero even when other terms are large.
  • Multiplying uncertain fractions does not create population evidence.
  • The lifetime term is detectable communicating duration, not total biological or technological lifetime.

References