“Why would you throw money away on rent when you could be building equity?” This is probably the most repeated piece of financial advice in America, and it is built on a comparison so flawed that it leads millions of people to make the wrong decision. The standard logic goes: my mortgage payment is $2,200 and rent is $2,000, so for just $200 more I'm “investing” in my own home. That framing ignores most of the actual costs of ownership and all of the opportunity costs of the capital you tie up in a house.

The rent vs buy question deserves better math. Here is what a rigorous comparison actually looks like.

Why the Common Comparison Is Wrong

When most people compare renting to buying, they line up one number against another: monthly rent versus monthly mortgage payment. This is wrong for several reasons.

First, a mortgage payment is not the total cost of owning a home. Property taxes, homeowner's insurance, maintenance, HOA fees, and closing costs on both the purchase and eventual sale add thousands of dollars per year that renters never pay. Second, the mortgage payment itself is mostly interest in the early years—on a 30-year mortgage at 7%, roughly 80% of your first payment goes to the bank, not to building equity. Third, and most critically, the comparison ignores the opportunity cost of the down payment. A $80,000 down payment on a $400,000 home is $80,000 that could be invested in a diversified portfolio. Over a decade, the difference in returns between a stock portfolio and home equity can be enormous.

To get the real answer, you need to compare total wealth outcomes for each path: the buyer's net worth (home equity minus remaining mortgage, plus any other investments) versus the renter's net worth (investment portfolio funded by the down payment plus the ongoing savings from lower housing costs).

The True Cost of Owning

The costs of homeownership break into two categories: the obvious and the overlooked. Understanding both is essential to an honest comparison.

The Obvious Costs

Mortgage interest. This is the cost of borrowing. On a $320,000 mortgage at 7%, you will pay roughly $447,000 in interest over 30 years—more than the original loan amount. Principal payments are not a cost; they are forced savings that build equity. But the interest is pure expense.
Property taxes. Typically 0.5% to 2.5% of assessed home value per year, depending on your state and municipality. On a $400,000 home at 1.2%, that is $4,800 per year, and it rises with your home's assessed value.
Homeowner's insurance. Usually $1,200 to $3,000+ per year, varying widely by location and coverage. Flood or earthquake zones can be significantly more.
Maintenance and repairs. The standard estimate is 1% to 2% of the home's value per year. On a $400,000 home, budget $4,000 to $8,000 annually. This covers everything from a new roof every 20 years to the water heater that fails on a holiday weekend.

The Overlooked Costs

Closing costs at purchase. Typically 2% to 5% of the purchase price. On a $400,000 home, that is $8,000 to $20,000 in loan origination fees, appraisals, title insurance, and other transaction costs that you never recover.
Closing costs at sale. This is the big one people forget. Real estate agent commissions plus transfer taxes and other fees typically run 6% to 8% of the sale price. Sell that $400,000 home (now worth $500,000) and you could pay $30,000 to $40,000 in selling costs. That is equity you built over years, handed to agents and the government at closing.
HOA fees. If applicable, these can range from $200 to $1,000+ per month and tend to increase over time.
Opportunity cost of the down payment and equity. This is the single most important hidden cost. Your down payment, closing costs, and the equity you build over time are capital that could be earning returns elsewhere. If the stock market returns 7% real and your home appreciates at 1% real (the long-run historical average for US housing), the gap compounds dramatically over time.

The True Cost of Renting

The renter's cost structure is dramatically simpler:

Monthly rent. Your primary housing cost. It increases over time, typically at or slightly above inflation.
Renter's insurance. Usually $150 to $300 per year—a fraction of homeowner's insurance.

That is essentially it. No property taxes, no maintenance, no closing costs, no HOA fees. The renter does not build equity in a home, but they also do not tie up capital in a single illiquid asset.

The critical piece of the renter's financial picture is what they do with the savings. A disciplined renter invests the down payment equivalent from day one, then invests the monthly difference between total ownership costs and rent. If total ownership costs are $3,500 per month and rent is $2,200, the renter puts $1,300 per month into a diversified portfolio. Over time, that portfolio compounds—and unlike home equity, it is liquid, diversified, and earns the full return of the capital markets.

The fair comparison is not “mortgage vs rent.” It is “total net worth of the buyer vs total net worth of the renter who invests the difference.”

The Variables That Matter Most

Not all inputs carry equal weight. Based on sensitivity analysis across thousands of scenarios, here are the variables in order of impact:

Time horizon. This is the single most important variable. Buying has large upfront costs (closing costs, moving expenses, the illiquidity of early equity). These costs need years to amortize. Under 3 years, buying almost never wins. Between 3 and 7 years, it depends heavily on the other variables. At 10+ years, buying wins in the majority of scenarios because the fixed mortgage payment becomes increasingly cheap relative to rising rents, and closing costs are spread over a longer period.
Home price appreciation rate. The long-run real (inflation-adjusted) appreciation of US housing has been roughly 0% to 2% per year, depending on the period and location. But local markets vary enormously. A home in a supply-constrained coastal city may appreciate at 3% to 4% real, while a home in a declining area may not keep pace with inflation.
Investment returns on the alternative portfolio. If the renter's portfolio earns high returns, renting becomes more attractive because the opportunity cost of tying up capital in a home is higher. The asset allocation of that portfolio matters significantly.
Rent growth rate. If rents are growing faster than inflation, buying becomes more attractive over longer periods because the mortgage payment stays fixed (on a fixed-rate loan) while the renter's costs keep climbing.
Mortgage interest rate. Higher rates increase the cost of borrowing dramatically. At 3%, a mortgage is cheap leverage. At 7%, interest costs dominate the early years and make the total cost of ownership substantially higher. Use a tool like eMortgage to compare current rates.
Tax bracket. The mortgage interest deduction can reduce the effective cost of borrowing, but only if you itemize deductions, and the 2017 tax law changes raised the standard deduction high enough that many homeowners no longer benefit.

Why Simulation Beats Spreadsheets

Most rent vs buy calculators—including the popular ones from the New York Times and other financial sites—ask you to plug in a single assumed rate for home appreciation, a single rate for investment returns, and a single rate for rent growth. They then project one deterministic outcome.

The problem is that none of these numbers are known in advance. Home prices could appreciate at 5% per year or decline 20% in a crash. Stock returns could average 10% or deliver a lost decade. Rent growth could be 2% or 6%. The single-scenario approach gives you a false sense of precision: it produces one answer that looks exact but could be wildly wrong.

A better approach is Monte Carlo simulation. Instead of assuming one future, you simulate hundreds or thousands of possible futures, each drawing from realistic distributions of returns, appreciation, and inflation. The output is not a single answer but a probability distribution: “buying wins in 73% of scenarios over 10 years, with a median net worth advantage of $45,000.”

This is fundamentally more useful than a spreadsheet answer because it tells you how confident you can be in the decision, not just what happens under one set of assumptions. It reveals the range of outcomes, including the tail risks—the scenarios where buying goes badly wrong or where renting leaves significant money on the table.

Historical simulation is equally powerful: instead of random draws, it replays every actual historical period. If you are considering buying and holding for 7 years, historical simulation shows you what would have happened across every 7-year period in the data—including those starting in 2006, 1999, and 1973. The results are grounded in real economic conditions, not theoretical distributions.

The Non-Financial Factors

This article focuses on financial math, but a complete decision includes factors that do not show up in any simulation:

Stability. Owning means no landlord can raise your rent 15% or decline to renew your lease. If you have children in school or deep community ties, that certainty has real value.
Customization. Homeowners can renovate, landscape, and modify their home. Renters are constrained by their lease terms.
Flexibility. Renting makes it easy to relocate for a new job, downsize after life changes, or move to a different neighborhood. Selling a home takes months and costs tens of thousands of dollars.
Forced savings. For people who would not otherwise invest consistently, the forced equity accumulation of a mortgage can be a genuine benefit. The best financial plan is the one you actually follow.

These factors are real and personal. Two people with identical financial situations can reasonably make different choices based on what they value. But you should make that decision with clear-eyed knowledge of the financial trade-offs, not with a vague sense that “renting is throwing money away.”

Run Your Own Numbers

The right answer depends entirely on your specific situation: your local housing market, how long you plan to stay, your mortgage rate, your investment strategy, and your risk tolerance. Generic rules of thumb cannot account for all of these variables interacting simultaneously.

The FIREwiz Rent vs Buy calculator runs a full Monte Carlo and historical simulation using your actual numbers. It shows you the probability that buying or renting wins, the expected net worth difference at each year, and the break-even timeline—all based on nearly a century of real market data rather than a single set of assumptions.

Plug in your home price, down payment, mortgage rate, expected rent, and time horizon. The simulator handles the rest: property taxes, maintenance, closing costs, opportunity cost of capital, and the full range of possible market outcomes. In a few seconds, you will have a more honest answer than any napkin math or single-scenario spreadsheet can provide.