The USS Enterprise-D has 42 decks. This figure comes from the ship’s technical specifications developed for Star Trek: The Next Generation, especially the licensed Technical Manual and related deck plans.
The Galaxy-class Enterprise is much larger than the Constitution-class Enterprise seen in the original series. Its 42 decks are distributed through the saucer and engineering sections, with facilities ranging from crew quarters and laboratories to shuttle bays, main engineering, cargo areas, and extensive maintenance spaces.
Fans sometimes encounter different numbers because deck plans, on-screen dialogue, and later reference materials do not always describe the ship with identical levels of detail. Some diagrams also distinguish numbered decks from Jefferies tubes, equipment spaces, and specialized structural areas. Nevertheless, 42 is the standard reference answer for the Enterprise-D’s total deck count.
The number is also easy to confuse with other Enterprise vessels. The Constitution-class Enterprise had far fewer decks, while the later Sovereign-class Enterprise-E is generally listed with 26 decks.