Soft cardinality is a parameterized text similarity function that uses a "soft count" instead of a crisp count to calculate the cardinality of the intersection between two texts. It includes a parameter p that controls the softness and extended weights like tf-idf for words. A parameterized resemblance coefficient is also used that balances the sizes of the two texts being compared. The approach was tested on semantic textual similarity tasks and achieved a higher rank mean score than other baselines like cosine similarity with tf-idf.