A system, method and program product for performing density checking of an IC design. The invention establishes an evaluation array for the IC design including an array element for each evaluation window of the IC design. The number of evaluation windows is based on a smallest necessary granularity. A single pass through shape data for the IC design is then conducted to populate each array element with a shape area for a corresponding evaluation window. Density checking is performed by iterating over the evaluation array using a sub-array. The sub-array may have the size of the preferred density design rule window. The invention removes the need for repetitive calculations, and results in a more efficient approach to density checking.