Upfront cash has an opportunity cost
A down payment and buying costs cannot be invested elsewhere. The renter starts by investing the difference between buying and rental upfront cash.
Housing cash flow and opportunity cost
Compare the wealth path of renting and buying
The model amortizes the mortgage, estimates ownership and rental costs, invests each month’s cash-flow advantage, and includes selling costs before comparing net wealth.
Plan with context
Rent versus buy is a wealth-path comparison, not a monthly-payment contest.
The right comparison follows cash flows and assets over the same horizon. This model invests whichever option has the monthly advantage and deducts selling costs before valuing home equity.
Principal becomes equity
Mortgage principal is a cash outflow but not a pure expense. It reduces debt and therefore increases the buyer’s net position, subject to transaction costs and home value.
Ownership costs extend beyond the loan
Property tax, insurance, HOA dues, maintenance, mortgage insurance, and selling costs can materially change the comparison.
Rent changes too
The rental path includes entered annual rent growth, renter insurance, upfront costs, and a refundable security deposit.
Breakeven depends on assumptions
Appreciation, investment return, rent growth, and transaction costs can move the crossover year substantially. Compare several conservative scenarios.
Lifestyle still matters
Mobility, maintenance responsibility, housing stability, liquidity, and local supply can matter more than a narrow modeled wealth difference.
Included
Mortgage amortization, down payment, buy and sell costs, tax, insurance, HOA, maintenance, PMI, appreciation, rent growth, deposit, investment return, optional tax benefit, charts, and annual ledger.
Not included
Market volatility, capital-gains taxes, renovation, utilities, moving costs, vacancy, landlord incentives, refinancing, itemized-deduction limits, or a property-specific forecast.
Use it well
Use local quotes, keep the tax benefit at zero unless you expect to itemize, and stress-test appreciation and investment return at least one percentage point lower.