K-12, a non-pathogenic strain of Escherichia coli that has been commonly used in the laboratory since its first isolation in 1922.

K¹², Inc., NYSE: LRN the technology-based online education company serving students in kindergarten through 12th grade.

K12, an obsolete process associated with older types of Kodachrome photographic film

K12, a mountain in the Karakoram mountain range of Pakistan

K₁₂, the Coxeter-Todd lattice

K–12 education, the North American designation for primary and secondary education.

K-12 (Kansas highway), a former highway in Kansas