गणित में, किसी समुच्चय का गणनांक "समुच्चय के अवयवों की संख्या" का एक मापन है। उदाहरण के लिए, समुच्चय A = {2, 4, 6} में 3 तत्त्व शामिल हैं, और इसलिए A का गणनांक 3 हैं।

In mathematics, the cardinality of a set is a measure of the number of elements of the set. For example, the set contains 3 elements, and therefore has a cardinality of 3. Beginning in the late 19th century, this concept was generalized to infinite sets, which allows one to distinguish between different types of infinity, and to perform arithmetic on them. There are two approaches to cardinality: one which compares sets directly using bijections and injections, and another which uses cardinal numbers. The cardinality of a set may also be called its size, when no confusion with other notions of size is possible.