Should You Buy a House If the Mortgage Is Double Your Rent? Here’s the Actual Math

“Our mortgage would be almost double what we pay in rent right now — is that insane?” I get a version of this question constantly, and the honest answer is: that comparison is almost never the right one to make.

Rent versus a future mortgage payment feels like the natural anchor because it’s the number you already know. But it’s comparing your payment today, on a place you may have deliberately under-bought for your current situation, against a payment on a home you actually want to live in long-term. The real question isn’t “how much bigger is this than my rent” — it’s whether the new payment fits your income, and whether the home is one you’ll be building equity in for years.

Why “Double My Rent” Is the Wrong Comparison

Here’s a real scenario a young couple brought to me recently. They were renting a smaller apartment for $1,400 a month and looking at a $360,000 house with an estimated $2,750 monthly payment (principal, interest, and taxes) — roughly double what they were paying to rent.

Their combined income was $140,000 a year, or about $7,800 a month after taxes. They had $45,000-$50,000 saved for a down payment and could still save $2,400 a month toward it in the meantime. On paper, the “double your rent” framing made them nervous. The actual math said something different.

At $140,000 in annual income, a $2,750 monthly payment works out to roughly 24% of their gross monthly income — comfortably under the 28% housing-cost guideline, before even accounting for the raises they were likely to see over time. The rent comparison was irrelevant. The income comparison is what mattered, and it said they were in good shape to buy.

The Numbers That Actually Determine Affordability

Skip the rent comparison and run these instead:

Price-to-income ratio. Divide the home price by your gross annual household income. A ratio at or below 3-4x is generally considered affordable in most markets; above 5x starts to strain most household budgets even at today’s rates, though high cost-of-living metros routinely run higher.

The 28/36 rule. Your total monthly housing cost — principal, interest, property tax, and insurance (often abbreviated PITI) — shouldn’t exceed 28% of your gross monthly income. Your total debt payments, including that housing cost plus car loans, student loans, and minimum credit card payments, shouldn’t exceed 36%. Most conventional lenders use a version of this DTI math to determine what they’ll actually approve you for, so it’s worth calculating it yourself before you fall in love with a listing.

What today’s rate actually does to the math. At the current 30-year fixed rate of roughly 6.5%-6.7%, a $360,000 loan runs about $2,275-$2,325 a month in principal and interest alone, before taxes and insurance. That’s a meaningfully bigger monthly hit than the same loan would have been at 2021’s sub-3.5% rates — see my full breakdown of mortgage rates and home prices in 2026 for the current-rate math and what’s likely ahead in 2027.

Consider Marcus and Elena, a different couple I’ve talked through this with. They earn $95,000 combined and were looking at a $310,000 home with an estimated $2,450 PITI payment. That’s about 31% of their gross monthly income — over the 28% guideline on its own. But they have no car payments and only $150 a month in student loan payments, keeping their total DTI at 33%, still under the 36% ceiling. Their case shows why you can’t stop at the housing-cost number alone; the full debt picture is what a lender — and you — should actually be weighing.

What the Rent Comparison Actually Gets Wrong

Rent and mortgage payments aren’t calculated the same way, which is the core reason comparing them directly misleads people:

Rent is set by a landlord based on the local market, not your personal finances — it has zero relationship to your income, your debt, or your savings. A mortgage payment is calculated from your specific loan amount, rate, and term, and a lender has already vetted it against your income before approving you.

Rent also often reflects a home you deliberately under-bought for your current life stage — a starter apartment while you save, a smaller place before a growing family. A home you’re buying is usually sized for where you’re headed, not just where you are, which naturally makes the payment bigger.

Finally, none of your rent builds equity. Even a mortgage payment that feels large is partly going toward an asset you own, not just monthly consumption — a comparison rent-to-mortgage ratios don’t capture at all.

Common Issues to Watch Out For

Anchoring on the rent multiple instead of the income math. I see this constantly — a payment that’s “double the rent” gets treated as inherently risky, when the real test is the 28/36 math above.

Ignoring other debts when estimating what you can afford. A big car payment or student loan balance can turn an affordable-looking housing payment into an over-leveraged one once total DTI is calculated.

Not stress-testing for a rate change if you’re using an ARM. If your loan isn’t a 30-year fixed, run the numbers at a rate 1-2 points higher to make sure a future reset wouldn’t break your budget. If rates do drop after you buy, refinancing is always an option worth revisiting later.

Forgetting property tax and insurance in the “mortgage” number. People often mentally price a house using just principal and interest, then get surprised when the full PITI payment — including property tax and homeowners insurance — is meaningfully higher.

Buying at the very top of what a lender approves you for. Being approved for a payment doesn’t mean it’s comfortable to actually live with once utilities, maintenance, and normal life expenses are added back in.

Looking Ahead: 2027 Outlook

With the 30-year fixed expected to stay in the 6.2%-6.5% range through most of 2027 according to major forecasters, the price-to-income math isn’t likely to get dramatically easier from rates alone. If you’re weighing buying now versus waiting, see my full 2027 mortgage rate and home price outlook for what’s actually likely to move next year.

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If a 15-year loan is on your radar as a way to build equity faster, see my 15-year vs. 30-year mortgage comparison for how the payment and total-interest tradeoffs actually compare at today’s rates. And if you’re still deciding between renting and buying at all, my apartment rental guide covers the renter’s side of that same decision.