: If your ETABS mass summary doesn't match manual calculations, check if you have "Element Self Mass" checked while also including dead load patterns with a multiplier of 1.0; this can double-count the self-weight. Common Pitfalls
Loads like lateral wind or soil pressure are forces , not masses . The summary will only include loads that have a vertical component and are assigned to the mass source. Review your diaphragm assignments to ensure mass is correctly lumped at the center of rigidity. etabs mass summary by story
This report is the primary tool for checking the "Mass Source" definition and ensuring that the dead loads, live load percentages, and self-weight are accurately represented at each floor level. How to Access the Mass Summary Table : If your ETABS mass summary doesn't match