Renting and buying are not really two prices for the same thing. Buying converts a large upfront payment and a stream of mortgage, tax, insurance, and maintenance costs into a house you own outright at the end. Renting keeps your upfront cash free to be invested elsewhere, in exchange for a payment that builds no equity. This calculator runs both paths month by month over your chosen time horizon so you can see which one actually leaves you wealthier, rather than guessing from the monthly payment alone.
Worked Example: The Calculator's Own Defaults
Load the calculator above with its starting values: a $350,000 home, 20% down, a 6.5% 30-year mortgage, $2,000 monthly rent, and a 10-year stay. Two numbers come directly out of the standard mortgage formula before any simulation even starts:
- Loan amount after the down payment: $350,000 × 80% = $280,000.
- Monthly principal & interest, from M = P × [r(1+r)n] / [(1+r)n - 1] with r = 6.5%/12 and n = 360: $1,769.79.
- Price-to-rent ratio: $350,000 home price ÷ $24,000 annual rent = 14.58, a mild lean toward buying by the common rule of thumb (below 15 favors buying, above 20 favors renting).
Running the full 10-year simulation, with property tax, insurance, maintenance, 3% home appreciation, a 25% marginal tax rate on mortgage interest and property tax, and the renter's savings invested at 7%, produces a home equity of about $232,998 against a renter investment portfolio of about $163,404 by year 10, with the buyer's equity overtaking the renter's portfolio as early as year 2. Change any single assumption, especially the appreciation rate or the investment return, and this break-even point can move by several years in either direction, which is exactly why the calculator recalculates it live rather than quoting a single rule of thumb.
Frequently Asked Questions
Q: The calculator assumes I invest 100% of the difference when renting is cheaper. What if I would not actually invest that money?
A: Then the renter investment portfolio figure overstates your real net worth under renting. It is the best case for renting, not a guarantee, since it assumes every dollar of savings gets invested rather than spent.
Q: How does the calculator handle the down payment and closing costs on the renting side?
A: It assumes the renter invests an amount equal to the buyer's down payment plus closing costs starting from day one, at your specified investment return, so the buyer's larger upfront outlay does not unfairly tilt the comparison.
Q: My break-even year came back as "Beyond timeframe." What does that mean?
A: Within the number of years you set for how long you plan to stay, home equity never overtakes the renter's investment portfolio. Extend the stay-years input, or adjust appreciation and return assumptions, to see when (or whether) buying would catch up.
Q: Why does raising the mortgage rate sometimes barely change the recommendation?
A: A higher rate raises the buyer's monthly cost, but it also shrinks the gap that would otherwise flow into the renter's investment portfolio, so both sides lose ground at once and the two effects partly cancel out.
This Calculator vs. the Mortgage Payment Calculator
Use this Rent vs. Buy Calculator when the actual question is whether you should buy at all, given a specific renting alternative. It exists to compare two entire financial paths, including opportunity cost, tax effects, appreciation, and rent inflation, not just to size a mortgage. Once you have decided to buy and want to drill into the mortgage itself, such as testing different down payments, loan terms, or rates to see how the monthly principal-and-interest payment changes, the Mortgage Payment Calculator is the more direct tool, without the renting side of the comparison attached.
Disclaimer: This calculator and guide are for educational purposes only and should not be considered financial advice. Always consult with a qualified financial advisor before making major housing decisions. Market conditions vary by location, and past performance does not guarantee future results.