Stardates

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USS Enterprise chronometer

Stardates are a fictional alternative to calendar dates in the Star Trek TV series, movies and books.  They are typically represented as a four or five-digit number with a decimal point followed by one digit, such as 1234.5 or 41234.5.  Three basic versions have been used by the various series and movies. 

More information may be found at Memory Alpha.

Timeline

Series	Stardate	Year1	Released
22rd Century
Enterprise	April 16	2151	2001-09-26
	47457.1	2370	2005-05-13
23rd Century
Discovery seasons 1 & 2	1207.3	2256	2017-09-24
	1201.7	2258	2019-04-18
Strange New Worlds	1739.1	2259	2022-05-05
	2344.2	2260	2023-08-10
Movies 11 12 13	2258.42	2258	2009-05-08
	2263.2	2263	2016-07-22
The Original Series	1312.4	2265	1966-09-22
	5943.9	2269	1969-03-14
The Animated Series	1254.4	2269	1973-10-27
	7403.6	2270	1974-09-14
Movies 1 2 3 4 5 6	7412.6	2272	1979-09-07
	9521.6	2293	1991-12-06
24th Century
The Next Generation	41153.7	2364	1987-09-28
	47988.0	2370	1994-05-23
Deep Space Nine	46379.1	2369	1993-01-03
	52861.3	2375	1999-05-26
Voyager	48315.6	2371	1995-01-16
	54973.4	2378	2001-05-23
Movies 7 8 9 10	48650.1	2371	1994-11-18
	56844.9	2379	2002-12-13
Lower Decks	57436.2	2380	2020-08-06
	58934.9	2381	2023-11-02
Prodigy	61103.1	2384	2022-02-03
	61302.7	2384	2022-11-17
25th Century
Picard		2399	2020-01-23
	78183.10	2401	2023-03-09
	1	2402	2023-04-20
32nd Century
Discovery seasons 3 & 4	865211.3	3188	2020-10-15
	865783.7	3190	2022-03-17
Starfleet Academy

¹ From Star Trek Chronology

The original series (TOS)

The original Star Trek TV series aired for three years in the 1960s.  There were also six motion pictures with the original cast, and the animated series and numerous books.  TOS stardates were four digits followed by one decimal.  There was no correlation between stardates and calendar dates, except that they generally increased in time during the series.  

TOS was set about 300 years after it aired, in the 2260s.  Star Trek: Discovery was originally set in 2256 with TOS stardates. Later, the show jumped to the 32nd century, with stardates consistent with TNG, but much later. Strange New Worlds also uses TOS stardates. The first prequel series, Star Trek Enterprise, was set in the 22nd century and generally did not use stardates.

The decimal digit was supposed to represent decimal time. According to The Star Trek Guide, the official writers guide for the series:

For example, 1313.5 is twelve o'clock noon of one day and 1314.5 would be noon of the next day. Each percentage point (sic) is roughly equivalent to one-tenth of one day.

This was demonstrated by the ship's chronometer in the TOS-Remastered episode, "The Naked Time," and later by Captain Varley's video logs in the TNG episode "Contagion."

Alternate Reality

An alternate reality in the Star Trek universe, sometimes referred to as the "Kelvin Timeline", was created in 2009, when a new movie franchise was started with the TOS characters and an all new cast in the movie Star Trek.  It also introduced an all new type of stardates, which is simpler and based upon year numbers in the Common Era.  These stardates are simply the current four digit year, followed by a decimal representing the ordinal day of year. Two stardates are given in the the 2009 movie, 2233.04 (when Kirk is born) and 2258.42, corresponding to January 4, 2233, and February 11, 2258, respectively.  The next movie, Star Trek Into Darkness, was released in 2013, and begins on stardate 2259.55, i.e. February 24, 2259. The third such movie, Star Trek Beyond, was released in 2016 and begins on stardate 2263.2: January 2, 2263. 

The Next Generation (TNG)

Star Trek: The Next Generation and its spin-offs, Star Trek: Deep Space Nine and Star Trek: Voyager, were followed by four movies with the TNG cast, and much later, by Star Trek: Picard and two animated spin-offs.  The stardates on all of these had five digits, usually with one decimal but occasionally more. 

These stardates had a general correlation with the calendar year, in which the first two digits incremented between TV seasons, and the following digits increasing from xx000.0 to xx999.9 during the course of the season. Stardates in the 24th century were counted from the year 2323, beginning with the first episode of TNG on stardate 41153.7, set in 2364, airing in 1987. Subtracting the first two digits during that season (41) from the year 2364 indicates that adding the first two digits of stardates in later seasons to 2323 gives the year of that season. So the TNG era of stardates is actually decimal time based on a count of years since 2323. 

During an “admiral's log,” Star Trek: Picard gave a stardate of 78183.10 in the fourth episode of season three, which aired on March 9, 2023, corresponding to an in-show date in 2401, 78183/1000 years after January 1, 2323. However, the finale gave a stardate of, “one,” perhaps suggesting a future reboot, with a new series of stardates for the 25th century…

Meanwhile, Discovery has moved to the 32nd century, with six-digit stardates starting with 865211.3, which is roughly consistent with TNG stardates. Star Trek: Starfleet Academy will be set in the same time frame. 

Contemporary stardates

Although stardates are used only in stories set centuries in the future, fans have used various methods to convert a contemporary calendar date into something that resembles a stardate. Several versions of the current moment are displayed above. The "epoch year" is the year each counts from.

This site

Star Trek: Picard gave the first stardate of the 25th century as 78183.10 on March 9, 2023. That is exactly 78183/1000 years since January 1, 1945, suggesting an epoch for the current era of stardates.  The "current stardates" made for this site use decimal time, so .00 represents midnight UTC/GMT, .10 is 02:24, .50 is noon, etc., just like Modified Julian Dates. The number of digits portray precision: two digits have a precision of 14.4 minutes, as opposed to 2.4 hours for one digit. Because the digits left of the decimal count about 2.74 units per day and ones to the right count 1.0 per day, there are some incongruities, such as not being entirely linear, but that's also true on the shows.

Star Trek Online

The Internet game Star Trek Online is set in the year 2409, but stardates within the game progress by 1000 every year in the present, beginning in the 87000s when the game was released in February, 2010, consistent with TNG stardates projected 400 years into the future, and rolling over on or near May 25 each year. That makes their epoch May 25, 1922. Since 2022, they are greater than 100000.00.

Negative TNG

Some, such as Andreas Schmidt and Steve Pugh, simply count stardates backwards from the TNG epoch, with stardate 0.0 occurring in 2323 and negative stardates prior to that.  This gives stardates in the current century that are six-digit negative numbers, such as -300000.0. Pugh divides the number into two parts: the right three digits are positive and increase from 000 to 999 throughout each year separately from the left-most digits, which are negative and approach zero by one each year, from -300 in 2023 to 0 in 2323.

Google/Main

Google Calendar formerly used stardates based upon Andrew Main's FAQ, which uses negative "issue numbers" in brackets before each sequential series of four-digit stardates, which increment by five units each day and each issue lasting about five-and-a-half years projecting, backwards from issue [19] during TOS in the 2260s, with the year 2023 occurring during issue [-26]. Issue [0] in this system represents the founding of the United Federation of Planets in the 2160s. 

TrekGuide

Others, such as TrekGuide.com, devised formulas such that the current stardate would be approximately the same as what Captain Picard, Sisko or Janeway would be putting in their logs in the 24th century, as portrayed in the most recent episode.  For instance, when one episode aired on September 28, 1987,  the stardate in the captain's log was 41153.7.  Thus, stardates in this system increment by one thousand per year, just as on TV, or on average about 2.7 per day.  The old TV seasons began in September and ended between May and July, so the contemporary stardate would roll over at some point in between, making stardate 0, the epoch, in 1946 (although others used January 1 as the rollover date).  

July 15, 1946, seems to be the exact date used to calculate a stardate on the episode "The Adhesive Duck Deficiency" of the TV show The Big Bang Theory, when Sheldon's log gives stardate 63345.3, corresponding with the date of the Leonid meteor shower that year, November 17, 2009.

Meyer

Trevor Meyer uses a formula based on one anomalous stardate from Discovery with 8 digits: 29141429.1. He uses an epoch of 25677 BCE, thousandths of a year, then simply drops the first three "invisible" digits and any leading 0's, leaving 5 digits or less. He explicitly states that the decimal digit is tenths of the day.

Julian Dates

Modified Julian Dates have also been used. Star Trek 30 Years Special Collector's Edition, published in 1996 by Paramount Pictures, states on page 81:

Few Star Trek topics generate as much heated debate as the stardate system, the time calculation used by the United Federation of Planets which was introduced to the classic series by Gene Roddenberry, who borrowed the notion from the Julian date currently used by astronomers. Developed by Joseph Justus Scaliger...the Julian time calculation measures the number of days elapsed since 1 Jan. 4713 BC, the date derived by Joseph Justus. In the case of the 30th anniversary of the air date for the original series (8 Sept. 1996), that's 2,450,335 days. To make it easier, astronomers only use the last five digits - making 50335 the Julian date for the Star Trek anniversary. For Star Trek, Roddenberry added a single digit after the decimal point (50335.2) to represent one of the 10 time measurements in a 24-hour period...Roddenberry borrowed the five-digit Julian date, shortening it to four digits and renaming it "stardate."

According to Kellam de Forest:

The original script for the pilot of Star Trek was titled "Menagerie" and we in the research department, De Forest Research, didn't see it until it was in script form and came to us to review just like any other Desilu script, or any other script from any other client. So we got this script, and the script originally had dates in it, like 2362, and months and days. I felt that that sounded a little awkward for the 23rd, 22nd century, so I thought that there should be another, another dating system. So I checked that, yes, the astronomers had a way of dating called a Julian day system, in which, based on the calculations of a 16th century French mathematician/philosopher that felt that because he devised this calendar with a thousands and thousands of year cycle and each day was numbered, and astronomers have used that since, because it, you don't have to bother with years and leap years and AD and BC. So I suggested to Gene Roddenberry that there was this system out there and the days would be numbered, and he picked up on that and coined the term "stardate" and dated the log and the dating in Star Trek with this stardate system.