Kaltbrunn has a population (as of ) of . , about 18.8% of the population was made up of foreign nationals. Of the foreign population, (), 44 are from Germany, 140 are from Italy, 418 are from ex-Yugoslavia, 18 are from Austria, 37 are from Turkey, and 107 are from another country.Der Kanton St. Gallen und seine Menschen in Zahlen - Ausgabe 2009 accessed 30 December 2009 Over the last 10 years the population has grown at a rate of 6.3%. Most of the population () speaks German (86.8%), with Serbo-Croatian being second most common ( 4.0%) and Albanian being third ( 3.0%).Swiss Federal Statistical Office accessed 7 January 2010 Of the Swiss national languages (), 3,206 speak German, 11 people speak French, 98 people speak Italian, and 8 people speak Romansh.
