The original Super Mario Bros. contains 8 worlds.
Released for the Nintendo Entertainment System in 1985, Super Mario Bros. divides its main adventure into eight numbered worlds, each containing four stages. This produces 32 standard levels, including overworld, underground, underwater, and castle courses. The final stage of each world is a castle where Mario confronts Bowser or one of his disguised minions.
The eight-world structure became one of the defining patterns of classic 2D Mario games. Worlds 1 through 7 gradually introduce tougher enemies and hazards, while World 8 serves as the climactic challenge. Players can use Warp Zones to skip ahead, but the game’s normal progression still ends at World 8-4, where Mario faces the real Bowser and rescues Princess Toadstool.
The number can be confusing because the game also contains secret areas and a famous Minus World glitch. Those do not create additional standard worlds in the original campaign. Super Mario Bros. Deluxe later added extra content based on the Japanese sequel, but that expanded release should not be confused with the original NES game’s eight-world layout.