Rent vs Buy, With the Missing Math

Field notes

The calculator carries both renting and buying through a time horizon and compares their ending net worth rather than stopping at monthly cash flow. Its model includes the renter's invested down payment and savings differences, while the buyer's side includes PMI, HOA fees, maintenance, taxes, insurance, utilities, and changing mortgage-interest deductions. A sensitivity grid tests home appreciation against stock-market returns, exposing how easily the result can flip.