Residential parking requirements are typically linked to residential unit sizes and guest ratios. For example, the table below refers to the off-street parking in Costa Mesa.
In this table there is a clear relationship between unit sizes and number of parking stalls. The city of Costa Mesa requires a combination of covered and open stalls to fulfill the parking requirement, and allows for reductions based on additional availability of covered spaces and reductions in guest parking in large developments. Depending on the jurisdiction and circumstances, there may exist exemptions or approvals that allow for a reduction in parking.
While the table is descriptive, I prefer to use an excel worksheet when calculating the required covered, open, and guest parking stalls.