What this calculator does
Drake Equation works out order-of-magnitude estimate of communicating civilisations in the galaxy from seven factors. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| New stars formed per year (R*) | A number. Starts at 1.5. |
| Fraction of stars with planets (fp) | A number. Starts at 1. |
| Habitable planets per system (ne) | A number. Starts at 0.4. |
| Fraction where life develops (fl) | A number. Starts at 0.13. |
| Fraction where intelligence emerges (fi) | A number. Starts at 1. |
| Fraction that develop detectable communication (fc) | A number. Starts at 0.2. |
| Average civilisation lifespan (L) (years) | A number, measured in years. Starts at 10000. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with new stars formed per year (r*)
Every other input is held at the calculator’s starting values while new stars formed per year (r*) varies. Select any row to load that scenario into the calculator.
| New stars formed per year (R*) | Estimated number of communicating civilisations (N) | New habitable-and-inhabited planets per year | Note |
|---|---|---|---|
| 0.75 | 78.000 | 0.039000 | A rough order-of-magnitude estimate; every factor here is an assumption, not a measurement |
| 1.13 | 117.520 | 0.058760 | A rough order-of-magnitude estimate; every factor here is an assumption, not a measurement |
| 1.5 | 156.000 | 0.078000 | A rough order-of-magnitude estimate; every factor here is an assumption, not a measurement |
| 2.25 | 234.000 | 0.117000 | A rough order-of-magnitude estimate; every factor here is an assumption, not a measurement |
| 3 | 312.000 | 0.156000 | A rough order-of-magnitude estimate; every factor here is an assumption, not a measurement |
| 4.5 | 468.000 | 0.234000 | A rough order-of-magnitude estimate; every factor here is an assumption, not a measurement |