How this US calculator works

The US version models a fixed-rate annuity mortgage, a year-by-year itemise-vs-standard-deduction decision (mortgage interest plus state and local taxes capped by the SALT cap), private mortgage insurance applied while loan-to-value exceeds 80%, and capital-gains tax on the renter's investment portfolio (long-term capital gains, with an optional 3.8% Net Investment Income Tax surcharge).

Both households start with the same liquid wealth — the down payment plus buy-side closing costs. The buyer spends it on the house; the renter invests it. Each month, the lower-outflow side invests the difference. Once a year, the buyer's tax effects (the mortgage interest deduction benefit when itemising, PMI dropping off as equity grows, property tax up to the SALT cap) are netted into the cash flow so next year's differential reflects them. The result is a year-by-year net-worth curve for both sides over your chosen horizon.

Use the inputs to set your home price, down payment, mortgage rate and term, federal marginal tax rate, state and local income tax rate, and the expected return on a stock/bond portfolio. The full methodology — including parameter sources for the 2025 standard deduction and SALT cap — is on the Methodology page.