X12

X12 or X-12 may refer to:
 * X12 (New York City bus)
 * ASC X12, the standard for the development and maintenance of Electronic Data Interchange standards for the United States
 * Convair X-12, an advanced testbed for the Atlas rocket program
 * Cummins X12, a diesel engine
 * SJ X12, a Swedish train.
 * X-12-ARIMA, software for seasonal adjustment of time series data