Qt may stand for:
- A quart, a measure of volume within traditional systems of units, equal to 2 pints
- A quarter, a unit of mass in Imperial units, equal to 2 stones or a quarter of an Imperial hundredweight; one quarter = 12.70058636 Kg.
- The Qt toolkit, cross platform graphical widget toolkit for the development of GUI computer programs
- "quiet", as in the (dated) slang expression "on the Q. T.", meaning "secretly"