Buy vs. Rent:
The Math No One Shows You

Every major buy vs. rent comparison ends at year 30. That is when the mortgage is paid off, so that is where the math stops.

It is also exactly the wrong place to stop.

The moment the mortgage disappears is the moment the owner’s financial picture changes completely. Monthly housing costs drop by more than half. The renter, meanwhile, is still paying rent — and it has been compounding at 3% per year for three decades. At age 61, that rent check is $5,113 per month. At 75, it is $7,734.

No major calculator models what that does to the renter’s investment portfolio over the following 20 years. This one does.

The Model

We used a $430,000 home (near the current national median), a 5% down payment of $21,500, a 30-year fixed rate of 6.4%, and 3% annual home appreciation. All costs on the ownership side are included. All costs on the rental side are included. Rent rises 3% per year.

Three renter scenarios run through the full 30 years:

What Ownership Actually Costs Each Month

Most buy vs. rent comparisons count only the mortgage. Here is the real number:

The maintenance and repairs line is often omitted in these comparisons. It should not be. A $430,000 home will need a roof, an HVAC system, a water heater, and other capital repairs over 30 years. Setting aside 1% of home value per year is a conservative but realistic budget for that reality.

PMI drops when the loan reaches 80% of home value. At 3% annual appreciation with normal paydown, that happens at month 49 — roughly 4 years in. Total PMI paid: $7,978.

If your target property carries an HOA, add that to the buyer column. Planned communities and condos often run $200 to $500 per month.

What Renting the Equivalent Property Costs

Year 1 monthly cost differential: $1,461. That is what the renter invests.

The Differential That Most Models Freeze in Place

As rent rises 3% per year and the mortgage payment stays fixed, the monthly gap closes steadily. The renter starts with $1,461 per month to invest. By year 25, the advantage has essentially disappeared. After that, the renter pays more per month than the owner.

The locked P&I is what drives this. Property taxes, insurance, and maintenance rise with the home’s value each year, but the mortgage payment never changes. By year 30, the renter’s monthly housing cost exceeds the owner’s by $314.

Year 7: Nearly a Tie

A common rule of thumb says buying takes five to seven years to make financial sense, once transaction costs and early-year interest are accounted for. Here is what the model shows at year 7:

The HYSA renter and the buyer are essentially tied. The S&P renter holds a meaningful lead, but only because of strong market returns in the early years when the monthly investment surplus is still near its peak.

Year 30: The Full Picture

Two findings stand out.

First, the buyer beats the HYSA renter at every point from year 7 forward. At year 30, the buyer holds $1,056,442 against the HYSA renter’s $698,180. The locked mortgage and forced equity accumulation outperform a savings account once rent inflation closes the monthly advantage window.

Second, the S&P 500 renter holds a significant lead at year 30: $2.98M against the buyer’s $1.06M. That is real. But it comes with conditions we will return to.

The Retirement Equation

The year-30 comparison treats the decision as if it ends at age 60. It does not.

A buyer who purchases at 30 owns their home outright at 60. When the mortgage is paid off, the monthly housing cost drops from $4,650 to roughly $2,158: taxes, insurance, and maintenance only. No payment. No landlord. A housing cost that is predictable and manageable on a fixed income.

The renter at age 60 is still writing a rent check for $5,113 per month. And it keeps rising.

Over 20 years of retirement, from age 60 to 80, the renter pays $953,000 more in housing costs than the owner.

A disciplined investor does not draw down principal to cover that difference. They live off portfolio income. A $2.98M portfolio at a 5% yield generates roughly $149,000 per year. Enough to cover the rent without touching the principal.

But that framing reveals a different problem. At age 61, 41 cents of every dollar of portfolio income goes to housing costs. The owner pays 17 cents of the same dollar. That is a gap of $2,955 per month in after-housing disposable income, and it widens every year as rent keeps rising.

The renter’s portfolio is larger. It also has to work much harder.

The owner holds a paid-off asset that can be sold, downsized, or used as a financial backstop. The renter’s portfolio is their only security, and it carries a large, open-ended housing obligation attached to it.

A Note on the Rate You Lock In

The model above uses 6.4%, today’s prevailing rate. Before drawing conclusions, it is worth understanding what that number actually represents historically.

Today’s 6.4% is not a penalty rate. It is the pre-crisis baseline.

The 30-year fixed mortgage has been tracked by Freddie Mac since 1971. Here is how the current rate compares to each era:

The 2010s and the 2020–2021 era of 3% and 4% mortgages were not normal. They were the product of emergency Federal Reserve policy: near-zero interest rates and the Fed actively purchasing mortgage-backed securities at $40 billion per month to directly suppress yields. Most economists place the structural floor for 30-year rates at 5.5% to 6.0% going forward, based on where long-term Treasury yields have settled in a post-QE world.

A buyer at today’s 6.4% rate is not overpaying historically. They are buying at roughly the same rate buyers faced throughout the entire 2000s.

The Hybrid Scenario: Buy Now, Refinance Later

Rates do move. The phrase “marry the house, date the rate” reflects a real strategy. If 30-year rates return toward the 4% to 5% range, a buyer who refinances at year 5 gets a materially different result.

Here is what a refinance to 4.5% at year 5 produces, assuming $6,000 in closing costs rolled into the new loan:

The buyer’s year-30 equity is identical either way — the home appreciates at the same rate regardless of the mortgage rate. But the renter’s portfolio shrinks significantly. A lower owner monthly cost means a smaller monthly surplus to invest. The crossover point moves six years earlier. The S&P renter’s net advantage after retirement housing costs narrows from $972K to $406K.

The refinance rewards the buyer and compresses the renter’s window simultaneously. You cannot count on rates falling. But if they do, the buyer captures the benefit. The renter does not.

The Three Renter Scenarios

The S&P 500 renter finishes ahead of the buyer at year 30, even accounting for retirement. But “invests the monthly surplus in the stock market for 30 years” is a behavioral commitment, not a spreadsheet entry.

In year one, the renter invests $1,461 per month. By year 20, the monthly surplus has shrunk to $410. By year 25, it is $74. After year 25, the renter pays more per month than the owner — and that premium comes out of a portfolio they need intact for retirement.

Staying disciplined through 25 years of a shrinking advantage, followed by 5 years of a housing cost penalty, followed by decades of retirement funding a $5,000-plus monthly rent obligation: that is what the winning renter scenario actually requires.

If that is you, renting and investing in equities is a legitimate path to greater wealth.

The conservative investor — HYSA, CDs, bonds — loses to the buyer at every point from year 7 forward. The locked mortgage beats savings account returns once the monthly advantage window closes. At year 30, the buyer holds $358,000 more than the HYSA renter, before accounting for the retirement housing premium.

The renter who spends the difference builds no housing wealth and no investment portfolio. The buyer’s equity is the only significant asset either of them accumulates. It is not a contest.

What the Model Cannot Measure

The numbers above assume the renter and buyer are comparing equivalent properties. That assumption often does not hold.

Renting a house with a yard in a quiet neighborhood is a different life than renting an apartment on the 14th floor of a building with two hundred neighbors. If you have children who need space, a dog that needs a yard, or a preference for the kind of permanence that comes with ownership, those factors belong in your decision and no spreadsheet captures them.

There is also the question of stability. A renter can be priced out at lease renewal, asked to leave when the landlord sells, or forced to move when a neighborhood changes around them. A homeowner is not subject to someone else’s financial decisions about the property. That stability has real value, particularly for families and anyone who has built deep roots in a community.

The decision to rent or buy is not only a financial decision. It never was.

The Honest Answer

The math does not say renting is always wrong. It does not say buying is always right. It says three things:

If you will invest the monthly cost differential in equities and sustain that discipline for 30 years, through a shrinking advantage window that flips negative in the final years and a retirement housing obligation that consumes roughly half your portfolio lead: renting can produce more wealth.

If you will invest conservatively, or are not certain you will invest consistently: buying produces more wealth and a dramatically lower-cost retirement.

If you will spend the difference: buy the house.

And if you have kids who need a yard, a community you want to stay in, or a need for the kind of stability that comes from owning your home: the math has already told you what you needed to know. Use it as a foundation, not a verdict.

Your Financial GPS

Sources and methodology: Home price: $430,000 (near U.S. national median, St. Louis Fed FRED / Census Bureau Q1 2026). Mortgage rate: 6.37% Freddie Mac PMMS, May 7, 2026. Home appreciation: 3% annually (10-year FRED historical average). Rent inflation: 3% annually. PMI: 0.5% annually until 80% LTV. Property tax: 1.1% annually. Maintenance reserve: 1% of home value annually. HYSA return: 4.5% APY (representative of current high-yield savings rates). S&P 500 return: 10.4% annualized (20-year historical average, 2005–2025; past performance does not guarantee future results). Refinance scenario: $6,000 closing costs rolled into new loan balance. Rate history: Freddie Mac PMMS archive, 1971–2026 (freddiemac.com/pmms).