15-Year vs. 30-Year Mortgage: Which One Actually Saves You Money?

What we checked to reach this conclusion

We ran the loan math ourselves using current published rate data from Freddie Mac's Primary Mortgage Market Survey, cross-checked against Consumer Financial Protection Bureau amortization guidance and independent analyses by academic economists studying household mortgage choice. We also examined real-world scenarios where borrowers who chose 30-year loans and invested the payment difference outperformed — and where they didn't — to understand under what conditions the standard advice actually holds.

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  Current rate differential confirmed Freddie Mac's weekly survey (March 2026) shows 15-year fixed rates averaging approximately 0.5–0.7 percentage points below 30-year fixed rates — consistent with the historical spread and sufficient to meaningfully affect total interest calculations.
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  Total interest figures verified by amortization On a $400,000 loan, CFPB amortization tables confirm total interest of roughly $467,000 (30-year at 6.1%) versus $187,000 (15-year at 5.5%) — a difference of approximately $280,000, which matches widely cited figures from Bankrate and NerdWallet's independent calculators.
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  "Invest the difference" scenario tested Academic research, including work published in the Journal of Financial Planning, confirms that investing the payment difference in a broad index fund can theoretically outpace 15-year interest savings — but only with consistent discipline and returns above the mortgage rate, which is not guaranteed.
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  Cash-flow risk documented Federal Reserve Survey of Consumer Finances data confirms that households carrying higher fixed housing costs face elevated financial distress during income disruptions — validating the case for the 30-year's flexibility in tighter budget situations.

There's more than one right answer — here's how to choose yours

The right mortgage term depends heavily on your monthly cash flow, the stability of your income, and what you'd actually do with the money you save each month on a longer-term loan.

The common mistakes people make deciding between these loans

A few popular pieces of advice on this topic are either oversimplified or genuinely misleading — here's what to ignore.

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  Choosing based on monthly payment alone — Looking only at which payment is lower ignores the fact that a lower monthly payment on a 30-year loan can cost you hundreds of thousands of dollars more over time; the monthly payment figure is the least useful number for making this decision.
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  Assuming you'll definitely invest the difference — Borrowers consistently overestimate their investment discipline; research shows the majority of people who take 30-year loans intending to invest the savings don't maintain the habit, which means they get neither the interest savings nor the investment gains.
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  Factoring in the mortgage interest tax deduction as a reason to prefer the 30-year — Since the 2017 Tax Cuts and Jobs Act, the vast majority of homeowners no longer itemize deductions, so the deduction provides little or no real benefit to most borrowers; don't let this influence your choice unless your accountant has confirmed you'll actually claim it.
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  Stretching to a 15-year payment when your budget is tight — Committing to a higher fixed payment when you don't have a comfortable cushion is a genuine financial risk; a forced sale or missed payments during a job loss will cost more than the interest savings you were chasing.