SQ, Sq, or sq may stand for:
- Sentience quotient, a measure of the total processing capacity of a brain
- Singapore Airlines IATA airline designator
- Sound quality, the characteristics of the output of a preamp, amp or sound system
- Space Quest, a series of adventure games by Sierra Entertainment
- Spiritual quotient, a term in popular psychology
- sq, the ISO code for the Albanian language (ISO 639 alpha-2)
- SQ (program), a program for compressing files on MS-DOS and CP/M
- Square, a type of measure of area, such as square foot (sq ft)
- Stereo quadraphonic, a matrix quadraphonic gramophone record format developed by CBS
- Subcutaneous injection, an abbreviation based on pronunciation
- Sûreté du Québec, the Quebec police force
- Systemizing quotient, a measure of a person's neurological tendency to systemize