Rent vs. Buy Calculator Guide
Real estate agents love to say renting is "throwing money away." It's a catchy line, but it skips over two things that matter more than almost anything else in the rent-versus-buy decision: how long you'll actually stay in the house, and what else that down payment could have been doing for you.
Where the "5-Year Rule" Comes From
You'll often hear that you shouldn't buy unless you plan to stay put for at least five years. It's not an arbitrary number — it's a rough estimate of how long it takes to recoup the transaction costs of buying and selling. Closing costs on the purchase typically run a few percent of the loan, and selling costs (agent commissions, title fees, repairs) commonly eat six to eight percent of the sale price. On a $350,000 home, that's potentially $25,000 or more just to exit the transaction — money a renter never has to spend.
In the early years of a mortgage, most of your payment is interest, not principal, so you're building equity slowly at first. Combine that with slow amortization and it usually takes several years of appreciation and paydown before your equity clears the hurdle those transaction costs create. Stay two years and even a hot housing market may not bail you out; stay eight or ten and the math tips firmly toward buying. This is exactly why the calculator above asks for "years to compare" — run it at 3 years, then again at 7 or 10, and watch the verdict flip. If you're weighing a shorter timeline specifically because you might refinance or relocate, it's also worth checking a refinance calculator to see how rate changes affect that breakeven window.
The Down Payment Is Not Free Money
Here's the part most rent-vs-buy conversations skip entirely: that down payment isn't just "saved up cash you're using well" — it's capital that stops earning a market return the moment it goes into a house. A $70,000 down payment sitting in a diversified portfolio compounding at a long-run historical stock market average could plausibly grow into a substantially larger sum over 10 or 20 years — the exact figure obviously depends on returns that are never guaranteed. Home equity, by contrast, only grows through appreciation and paydown, and it's illiquid until you sell or borrow against it.
This doesn't mean renting always wins. It means the true cost of buying includes an opportunity cost that a simple "rent vs. buy" cost comparison doesn't show unless you go looking for it. If you want to see what that same down payment might have grown into had it gone into the market instead of a house, run it through the investment calculator using your expected time horizon and a conservative return assumption, then compare that growth against the net proceeds this calculator estimates from selling the home. The gap between those two numbers is the real price of choosing home equity over a portfolio — and it's often bigger than people expect, especially over stays longer than a decade.
Putting the Two Ideas Together
The practical takeaway is that timeline and opportunity cost pull in opposite directions. A longer stay makes buying look better by amortizing the transaction costs over more years, but it also gives the "invested down payment" scenario more time to compound, which can make renting-and-investing look better too. There's no universal answer — it depends on your mortgage rate, expected home appreciation, and what return you'd realistically expect from investing instead. If you're also carrying other debt alongside a potential mortgage, it's worth sorting out priorities with a credit card payoff calculator before committing a large lump sum to a down payment. And because a mortgage decision this size interacts with taxes, retirement savings, and estate plans, treat any of this as a starting point for your own research rather than a substitute for advice from a financial or tax professional who knows your full picture.