Stardate Calculator
Earth date ↔ Star Trek TNG-era stardate.
Overview
The Stardate Calculator converts between an Earth date and the Star Trek: The Next Generation-era stardate format used throughout 24th-century episodes. Enter a Gregorian date and you get a five-digit stardate with a decimal fraction, or enter a stardate and it tells you the corresponding Earth date.
Useful for Star Trek fans dating fan fiction, prop designers stamping in-universe documents, RPG game-masters running Trek campaigns, fan-wiki editors verifying episode dates, and anyone who wants their journal entries timestamped like a Federation captain's log.
How it works
The TNG-era convention used here treats each Earth year as 1,000 stardates, with stardate 0 set to the start of the year 2323. So a stardate of 45000.0 is roughly the start of 2367 (45000 ÷ 1000 + 2323 = 2368, off by one because the year is the integer part). The fractional component is the elapsed fraction of that year, with a single decimal place giving roughly 36-hour resolution.
This is the cleanest of several conflicting conventions used across the Trek franchise — the Original Series stardates were notoriously non-sequential, and DS9 / Voyager loosely followed the TNG scheme. Real-world calendars never use stardates; the system is purely a piece of in-universe set dressing translated here into a deterministic formula.
Examples
2026-05-18 → stardate −29662.6 (negative because the date is before 2323)
2323-01-01 → stardate 0.0 (TNG-era epoch)
2367-01-01 → stardate 44000.0 (Encounter at Farpoint, TNG pilot, was ~41153)
2400-12-31 → stardate 77999.7
FAQ
Which stardate system does this use?
The TNG-era convention: 1000 stardates per Earth year, anchored at 2323. The Original Series stardates used in 1966–69 episodes were inconsistent and are not mappable to a formula.
What does the decimal part mean?
The fractional year. .5 is approximately mid-year, .0 is January 1, .9 is late December. With one decimal place you get roughly 36-hour granularity.
Why is the present-day stardate negative?
Because the TNG epoch is set in the year 2323, dates before then map to negative stardates. The Federation simply does not exist yet, narratively speaking.
Is the calculation canon?
The franchise has never published an exact in-universe formula. The 1000-per-year TNG rule is the most consistent fan reconstruction and was used (roughly) by writers from 1987 onward.
Can I use it for Star Trek: Discovery dates?
Discovery's stardates are loosely TOS-era and do not fit either TOS or TNG conventions cleanly. The producers explicitly leave them flexible for storytelling purposes.