Skyband queries are very important for decision-making applications. To incorporate the Skyband operator into the database system, the problem of Skyband cardinality estimation must be solved, i.e., estimating the number of the Skyband elements returned by Skyband queries, which is very important for extending the query optimizer’s cost model to accommodate Skyband queries. This paper proposes a space and time efficient approach to estimate the Skyband cardinality, which is based on the generalized form of the Inclusion-Exclusion Principle. Experimental results show that the proposed approach can estimate the Skyband cardinality accurately.