When Commander Benjamin Sisko welcomed the first guest from the Gamma Quadrant in the Alpha Quadrant, a Tosk, he told him that he traveled almost ninety thousand light years through the wormhole. (DS9: "Captive Pursuit")
The exact length of a light year depends on the exact length used for one "Earth year". The IAU uses a Julian year of 365.25 days, while other sources may use a Gregorian year of 365.2425 days, or another year altogether.
|Source||year (days)||light year (kilometers)||light year (miles)|
|365.242199||9.460 528 4×1012||5.878 499 81×1012|
‡ Note that while Yahoo separately reports a year length of 365.24220 days, its rounding of the light year length to five digits works out to a year length of ~365.2411 days.