Rent vs Buy: The Real Math Behind the Decision

Why monthly payment comparisons lie

Rent of $1,800 looks cheaper than a $2,200 mortgage payment, and rent of $1,800 looks worse than a $1,600 payment. Both comparisons are meaningless, because part of the mortgage payment is not a cost at all: the principal portion buys you equity.

The real question is how much of each option is gone forever. Rent is 100% gone. But mortgage interest, property tax, insurance and maintenance are gone too; only the principal repayment builds wealth.

So a $2,200 payment might contain $900 of principal (savings) and $1,300 of true cost, making it cheaper than $1,800 rent. Or it might contain $300 of principal and $1,900 of true cost, making renting the clear winner. You cannot know without the breakdown.

The 5% rule

The 5% rule, popularized by researcher Ben Felix, says the unrecoverable costs of owning run about 5% of the home's value per year: roughly 1% property tax, 1% maintenance, and 3% cost of capital (the return your down payment could have earned plus mortgage interest).

Apply it: a $500,000 home costs about $25,000 a year in unrecoverable costs, or $2,083 a month. If you can rent an equivalent place for less than that, renting wins financially. If rent costs more, buying wins.

The rule is a shortcut, not gospel. Adjust it: low property-tax areas might use 4%, high-tax or high-maintenance markets 6%. But it forces the right comparison, yearly true cost against yearly rent, instead of payment against rent.

The true cost of buying, itemized

Start with the down payment's opportunity cost. $80,000 down on a $400,000 home, invested at 7% instead, would earn $5,600 a year. That invisible cost is real.

Add closing costs of 2 to 5% of the price, paid once but amortized over your stay: on a 5-year stay, 3% closing costs equal 0.6% per year. Add maintenance averaging 1% of value yearly ($4,000 on $400,000), homeowner's insurance, and property tax, often 1% or more.

Finally, selling costs 6 to 8% in agent commissions and fees. On a $400,000 sale that is $24,000 to $32,000, which punishes short stays brutally. Short ownership is where buying loses most often.

The true cost of renting, itemized

Renting's costs are simpler but grow relentlessly. At $2,000 a month rising 3.5% a year, year-ten rent is 2,000 x (1.035)^9 = about $2,726 a month. Over ten years you will pay roughly $281,000 in total rent.

Renters also face the opportunity question in reverse: the money not tied up in a down payment can be invested. If our renter invests the $80,000 they did not put down at 7%, it grows to about $157,000 in ten years, offsetting much of the "thrown away" rent.

The honest renter's math therefore credits the invested down payment and debits rising rents. The honest buyer's math credits forced savings through principal and debits every unrecoverable cost. Same framework, both sides.

The breakeven horizon

Breakeven horizon is the stay length where buying's total costs drop below renting's. Take the $400,000 home with 10% down: the $360,000 loan at 6.5% for 30 years costs about $2,276 a month in principal and interest, plus roughly $700 in tax, insurance and maintenance, for a true monthly cost near $2,975.

Against $2,000 rent growing 3.5% yearly, buying starts far behind because of closing costs and the interest-heavy early payments. But rent compounds upward while the mortgage payment stays fixed, and principal repayment accelerates. Typically the lines cross around year 7 to 9 in this scenario.

The practical rule: if you will stay fewer than about 5 years, renting usually wins. Beyond 7 to 10 years, buying usually wins in stable markets. Between 5 and 7 is the gray zone where the calculator and your local numbers decide.

The non-math factors that decide

Mobility has a price. A renter can chase a better job across the country with 30 days' notice; an owner faces months of selling costs and stress. Early in a career, that flexibility is worth real money.

Lifestyle cuts both ways. Owners control their space and lock in housing costs; renters outsource repairs and avoid surprise $8,000 roof bills. Know which kind of uncertainty bothers you more.

Then there is discipline. A mortgage is forced savings: every payment builds equity whether you feel like saving or not. Renters who invest the difference diligently can match or beat owners, but most do not. Be honest about which type you are.

Quick sanity checks

The price-to-rent ratio: divide the home price by annual rent for an equivalent place. $400,000 / ($2,000 x 12) = 16.7. Below 15 favors buying, above 20 favors renting, and 15 to 20 is the gray zone where details decide.

The 28/36 rule for affordability: housing costs under 28% of gross monthly income, all debts under 36%. These are ceilings, not targets. A house you can barely afford turns every repair into a crisis.

Finally, run your own numbers with the rent-versus-buy calculator linked below, using your city's taxes, your expected stay and realistic rent growth. Rules of thumb start the thinking; your numbers finish it.

A full side-by-side: ten years of numbers

Run the buyer: $400,000 home, $40,000 down, $360,000 loan at 6.5% for 30 years. The principal-and-interest payment is about $2,276 a month. After ten years you have paid roughly $273,000 in payments, of which about $218,000 was interest and only about $55,000 reduced the loan balance. Add roughly $84,000 in tax, insurance and maintenance over the decade.

Run the renter: $2,000 a month rising 3.5% yearly totals about $281,500 over ten years. But the renter invested the $52,000 they did not spend on down payment and closing costs. At 7% that grows to roughly $102,000. The renter "threw away" $281,500 in rent but built $102,000 in investments.

Now compare wealth: the buyer holds about $55,000 of paid-down principal plus any appreciation. At 3% yearly appreciation the home is worth about $538,000, a $138,000 gain, and buying wins clearly. At 0% appreciation the buyer is barely ahead after all costs. The appreciation assumption, not the monthly payment, decides the winner. Always run both scenarios.

Special cases that flip the answer

In very expensive cities the math can favor renting for decades. When price-to-rent ratios climb above 25 or 30, as in parts of San Francisco or New York, ownership costs dwarf rents so thoroughly that invested savings win for a generation. Local numbers beat national slogans.

House hacking flips the math the other way. Buy a multi-unit property, live in one unit and rent the others; the rental income can cover most of the mortgage, turning the 5% rule upside down. It requires landlord effort, but the arithmetic is transformative.

Uncertainty has a price tag. If there is even a 30% chance you move within five years, the 6 to 8% selling costs make buying a gamble, not a plan. And in inflationary periods, a fixed-rate mortgage is a hedge: your payment stays frozen while rents climb, so long-term owners gain the most.

Frequently asked questions