Is car parking (basement or stilt) a major cost driver in commercial projects?

Yes, parking is frequently one of the larger cost drivers in commercial projects because most authorities mandate minimum parking ratios tied to built-up area and occupancy type, and basement parking in particular adds excavation, retaining structure and waterproofing cost. Stilt parking is generally less expensive than basement parking but still consumes ground-floor area that could otherwise be leasable. Confirm your required parking ratio with the sanctioning authority before finalising the calculator's basement toggle.