Stardate to Gregorian Date
Gregorian Date to Stardate
How does this work?
Warning: Geek stuff beyond this point.
The trick is to know what numbers will work
I started with Andrew Main’s Stardates in Star Trek FAQ. In his article FAQ, Mr. Main notes that in the episode “Charlie X,” the Enterprise crew celebrated a Thanksgiving holiday and that Captain Kirk recorded a log dated Stardate 1533.6. Mr. Main then assumed that the highest stardate that was stated in the series – Stardate 5943.9 in “All Our Yesterdays” – takes place about 2 1/2 years later. This corresponds to a rate of about 18,000 seconds per stardate unit. Working back from November 21 places the beginning of the TOS “epoch” on January 6, 2266
For the second through sixth feature films, Mr. Main compares the stardates and relative Gregorian dates of the movies and determined that the stardates slowed down by a factor of about 10, or about 180,000 seconds per stardate unit. For the first movie, Mr. Main required the stardate range to slow considerably from both the series and the rest of the movies. Mr. Main figured a rate of around 576,000 to 864000 seconds per stardate unit would be needed to “fill the gap.” I went with 600,000 seconds per stardate unit. Placing the two movies on a timeline relative to the Original Series, I determined the start for the Epoch for the first movie to begin on March 11, 2270/Stardate 7320 and for the remaining films to begin on July 25, 2284/Stardate 8076.
For the spin-off series (Next Generation, Deep Space Nine, and Voyager), the writers marked out each season by using 5-digit stardates, starting at 41153.7 for the first episode of The Next Generation, increasing the thousands digit by one each season. This continues to be used to a lesser extent in Discovery, Lower Decks, Prodigy, and Picard. There are two episodes that give Stardates that are relatively close to a specific date on the Gregorian calendar. The first, from the Voyager episode “Homestead,” places Stardate 54868.6 a few days after the crew celebrated “First Contact day,” referring to the events in the movie Star Trek: First Contact, which occurred in the Star Trek timeline on 5 April 2063. The second, the Picard episode “Imposters,” places stardate 78186.03 about 3-4 days before the “Frontier Day” event that marks the 250th anniversary of the launching of the Enterprise NX-01, as seen in the Enterprise episode “Broken Bow,” In “Broken Bow,” there’s a log entry dated April 16, 2151, just after the NX-01 was launched.
Taking the stardates for “Homestead” and “Imposters” as both being in the month of April, I found that a happy medium to be 31140 seconds per stardate unit. I calculated that this fourth epoch would meet the third epoch at Stardate 18151.7 with a corresponding Gregorian Calendar date of January 14, 2342.
Note: I have not attempted to calculate Stardates for episodes that take place chronologically prior to the original series, namely the first two seasons of Discovery and Strange New Worlds. In my ‘head cannon,’ stardate 1 of the TOS epoch corresponds to the start of Kirk’s five-year mission as depicted in TOS.