Calc or CALC may refer to: Short for calculation, calculator, or calculus Windows Calculator, also known by its filename LibreOffice Calc, an open-source spreadsheet application similar to Microsoft Excel The Anglo-Saxon rune ᛣ, representing /k/ The Calcarea class of calcareous sponges The Latin American and Caribbean Unity Summit, known in Spanish as the Cumbre de América Latina y el Caribe (CALC) The Canadian Association of Lutheran Congregations (CALC) See also Calque Calc–silicate rock