The Rent vs Buy Question Everyone Gets Wrong

Type “rent vs buy calculator” into Google and you’ll find dozens of tools that boil the decision down to one comparison: mortgage payment versus rent payment. If the mortgage is lower, buy. If rent is lower, rent. Simple, clean, and missing about half the real picture.

Here’s what’s interesting — homeownership has costs that never show up on a mortgage statement. Maintenance alone typically runs 1-2% of your home’s value every single year (a $400,000 house means $4,000-$8,000 annually just keeping things from breaking). Add property tax, insurance, and the 6-8% in agent commissions and closing costs you’ll pay when you eventually sell, and the math shifts substantially from what a bare mortgage-vs-rent comparison shows.

The Piece Almost Nobody Calculates: Opportunity Cost

A 20% down payment on a $400,000 home is $80,000. That money has to come from somewhere, and once it’s in a house, it’s not earning anything else. If you rented instead and invested that $80,000 in a simple index fund, historical long-run returns (the S&P 500 has averaged roughly 7% annually after inflation over many decades) would have it compounding the entire time you’re renting.

This calculator treats that down payment as an investment that grows in the renting scenario, then compares it against the equity you’d build in the buying scenario. That’s the actual apples-to-apples comparison — not “mortgage vs rent,” but “what happens to my money under each path.”

Why the Break-Even Year Matters More Than the Monthly Payment

Buying almost always starts out financially worse than renting, because of upfront closing costs and the fact that early mortgage payments go mostly toward interest, not equity. But here’s the thing — rent tends to rise every year, while a fixed-rate mortgage payment doesn’t. Eventually the lines cross. That crossing point is the break-even year, and it’s a far more useful number than comparing today’s payments side by side.

If you’re planning to move again in 2-3 years, a break-even year of 8 is a strong signal to keep renting. If you’re putting down roots for a decade or more, the same number tells a very different story.

Example Calculation

What Changes the Answer the Most

Three inputs swing the result more than anything else. Mortgage rate matters enormously — a 2-point difference in rate can shift the break-even year by 3-5 years on its own. Home appreciation is the second lever; in flat or declining markets, buying’s advantage shrinks or disappears. And the investment return assumption for the renting scenario matters too — assume a higher market return and renting looks more competitive for longer, since the down payment grows faster on the sidelines.

None of these are predictable with certainty, which is exactly why running a few different scenarios (try the sliders with slightly higher and lower rates) gives a more honest picture than trusting a single number.

What This Calculator Doesn’t Capture

This is a financial model, not a life-decision model. It doesn’t weigh the stability of owning, the flexibility of renting, the cost and hassle of moving, or the value of being able to renovate a space that’s yours. Plenty of people buy for reasons that have nothing to do with which option wins on a spreadsheet — that’s a legitimate choice the math here isn’t trying to override.

Frequently Asked Questions

Why do most rent vs buy calculators give misleading answers?

Most calculators only compare the mortgage payment to the rent payment. They skip maintenance costs (typically 1-2% of home value per year), the opportunity cost of tying up your down payment, and the 6-8% in closing costs when you eventually sell. Leaving those out makes buying look better than it usually is.

What is the opportunity cost of a down payment?

If you rent instead of buying, your down payment money doesn’t disappear — it can be invested. This calculator assumes that money grows at your chosen investment return rate, and compares that growing balance against your home equity over time.

How accurate is the break-even year?

The break-even year depends heavily on your assumptions for home appreciation, rent growth, and investment returns. Small changes to those inputs can shift the break-even point by several years, so treat it as a directional estimate rather than a precise prediction.

Does this calculator include selling costs?

Yes. It assumes roughly 7% of the home’s future value would go to real estate agent commissions and closing costs if you sold at the end of your selected timeframe, which is a standard industry estimate.

Is buying always better if I stay long enough?

Usually yes, since fixed mortgage payments eventually become cheaper than rising rent, and equity accumulates. But this isn’t guaranteed — if home appreciation is weak or investment returns on the down payment are strong, renting can stay ahead for decades in some scenarios.