J3

J3, J03, J 3 or J-3 may refer to:

Roads

 * County Route J3 (California)
 * Malaysia Federal Route J3

Submarines

 * Junsen type submarine
 * HMAS J3, an Australian submarine

Aircraft

 * Junkers J 3, a German Junkers aircraft
 * J-3, a U.S. Navy airship
 * Piper J-3, a 1938 light aircraft

Other uses

 * J3 perturbation, gravitational force caused by an imperfect symmetry north–south of an object being orbited
 * J3 Operations Directorate, part of the US Joint Chiefs of Staff
 * GS&WR Class J3, an Irish steam locomotive
 * JAC J3, a subcompact car produced by JAC Motors
 * Janko group J3, in mathematics
 * Eupheme (temporarily designated S/2003 J 3), a satellite of Jupiter
 * J3 League, Japanese football league
 * Northwestern Air IATA code
 * J03: acute tonsillitis ICD-10 code
 * Triangular cupola, Johnson Solid number 3
 * Samsung Galaxy J3, a smartphone by Samsung
 * J3 battlecruiser, a British military vessel design from 1920s
 * LNER Class J3, a class of British steam locomotives