IN3

IN3, or similar, may refer to:

• cubic inch (in³), a unit of volume
• Indiana State Road 3, a road in the eastern part of the U.S. state of Indiana.
• Indiana's 3rd congressional district, a congressional district in the U.S. state of Indiana
• Internet Interdisciplinary Institute, the research body of the Open University of Catalonia
• Iodine azide, chemical formula IN₃