Abacus (disambiguation)

Abacus may refer to:

* Abacus, or "counting frame"
** Abacus system, mental calculation method
** Abacus logic, a logic equivalent to the mathematical abacus
* Abacus (architecture), a flat slab forming the uppermost member or division of the capital of a column
* Abacus Harmonicus, an ancient diagram which showed the structure and placement of the keys of a particular musical instrument.

;Organisations:
* Abacus 5, an action sports manufacturing and distribution company that is based out of Shanghai, China
* Abacus Arms, a small arms company in the United States.
* Abacus Federal Savings Bank, an overseas Chinese bank in the United States.
* "Abacus Records", an imprint of Century Media Records

;Other:
* Operation Abacus, the Canadian military operation to restore vital services if the year 2000 caused disruption.