Housing decisions combine financial assumptions and personal priorities. This model isolates equal cash resources, dated housing costs and realizable wealth. A favorable result is conditional on the inputs, not a promise about markets or a recommendation for every household.
Follow both cash ledgers
The renter receives the buyer’s cash-to-close as initial liquid capital, unless separately entered renter fees use some cash. Each month both receive the same budget. Positive remainders are invested; a shortfall uses held cash then investments. Negative balances are disclosed with an entered financing rate. This keeps the comparison from giving one path extra money simply because its housing payment is lower. When the budget is left blank, the model uses the higher housing cost for that month as the common budget; an entered fixed budget instead exposes any shortfall. Turning initial investment off preserves the starting liquid principal as cash at zero return, while later monthly surpluses still enter the investment portfolio. The down payment becomes home equity rather than disappearing as an expense. Read the starting-capital receipt together with the monthly ledger to understand where each path’s money goes. A negative portfolio represents a modeled funding gap, not evidence that borrowing would be available on those terms. Both the assumed return and the financing rate can materially affect the outcome.
Separate ownership from sale proceeds
Only scheduled principal and interest are fixed for the entered fixed-rate loan. Taxes, insurance, upkeep, HOA and rent follow the stated assumptions. At the actual sale, the loan and expenses are deducted once. There is no continuing hypothetical home or mortgage in the post-sale path. Before that sale, buyer wealth includes the modeled amount available from immediate liquidation, rather than the full home price or gross equity alone. At the planned sale, net proceeds move into the portfolio and the former owner pays rent on the same rental path used for the renter. This lets the comparison date differ from the move-out date without creating a free-housing period. Unrecoverable costs exclude down payment and principal repayment, while housing cash outflows include scheduled principal because it must still be funded. Optional sale-tax inputs are scenarios requiring your own eligibility review; the calculator does not infer an exclusion from ownership duration. Check the sale receipt for the home value, selling costs, mortgage payoff and entered tax treatment before treating equity as spendable cash.
Stress assumptions, not probabilities
The appreciation-return grid holds rent growth fixed and previews each pair without applying it. Driver comparisons change one input at a time. A long stay does not guarantee a buying advantage, and no crossing says nothing beyond the finite horizon. Verify taxes and quotes independently. Grid cells show a signed modeled wealth difference, not a probability of success; an outlined sign change only locates a boundary between sampled combinations. Previewing a cell leaves your current assumptions intact until you choose Apply. The driver list uses disclosed changes so you can see which single assumption moves this scenario most, rather than treating unlike inputs as interchangeable risks. Nominal amounts describe future dollars. Today’s-dollar wealth uses the same inflation factor for both paths at the selected date, while cash-flow present values discount payments at their individual dates. Keep those measures separate when reading the chart and tables. Optional federal deductions use the explicitly reviewed tax-year assumptions, not a complete tax return. Household flexibility, maintenance effort, lease terms and the ability to fund shortfalls remain personal considerations outside the signed financial verdict.