- Used (as –30–) to indicate the end of a newspaper (or broadcast) story, a copy editor's typographical notation.
- The number of days in the months April, June, September and November
- The number of cars in the F-Zero franchise.
- The total number of major and minor keys in Western tonal music, including enharmonic equivalents
- The minimum age for United States senators
- In years of marriage, the pearl wedding anniversary
- The duration in years of the Thirty Years' War - 1618 to 1648.
- The code for international direct dial phone calls to Greece
- The designation of Interstate 30, a freeway that runs from Texas to Arkansas
- The designation of U.S. Route 30, a highway that runs from Oregon to New Jersey
- Various other routes have been numbered "30"; for example, New York State Route 30 which runs from the Pennsylvania border to the Canadian border
- The number of tracks on The Beatles' eponymous album, usually known as The White Album
- A stage in young adulthood
- Part of the name of:
According to Zapamundo and myself, 30 is a crazy-huge number of squats to start with on an easy squat challenge.
I have a feeling that tomorrow is going to be a LOT more difficult...I'm already walking funny.