15-Year vs 30-Year Mortgage

What 15-Year and 30-Year Mortgages Actually Are

A fixed-rate mortgage locks the interest rate for the life of the loan. Principal and interest stay constant; taxes, insurance, HOA dues, and PMI can change. What differs between a 15-year and a 30-year is how the same principal is distributed across monthly payments.

A 30-year loan stretches repayment across 360 payments, which lowers the required monthly principal-and-interest amount. The balance declines slowly, and interest accrues over a longer window. A 15-year loan compresses repayment into 180 payments. The required payment is higher, the balance falls faster, and the loan is retired in half the time.

Lenders typically price shorter-term fixed mortgages at lower rates because the institution takes on less duration risk. The actual spread depends on the lender, borrower profile, property, and market conditions on the day of lock. Compare Loan Estimates, not advertised rates.

Rates from Freddie Mac's Primary Mortgage Market Survey, October 15, 2026. Payment and interest figures use the illustrative $400,000 loan at 7.00% (30y) and 6.25% (15y) shown below. Run the mortgage calculator at your actual loan amount for numbers specific to your case.

Monthly Payment Math: The Gap Most Buyers Underestimate

The most visible difference is the monthly payment. Take a hypothetical $400,000 loan. At a 30-year fixed rate of 7.00%, principal and interest run approximately $2,661.21 per month. At a 15-year fixed rate of 6.25%, the payment rises to approximately $3,429.69. The monthly gap is $768.48 — even though the 15-year loan carries the lower rate.

That gap is where most budgets break. A borrower comparing only advertised rates could miss the cash-flow impact of compressing repayment into half the schedule. The payment calculation depends on both the rate and the term, using the same principal and consistent assumptions across scenarios.

Principal and interest are not the entire housing cost. Depending on the loan and property, add property taxes, homeowners insurance, PMI, HOA dues, and maintenance. A mortgage calculator that displays only principal and interest is not a complete cost of ownership.

Test both payments against your full budget: existing debt, retirement contributions, emergency savings, and predictable maintenance. If the 15-year payment leaves no room for a temporary income drop or a major repair, the interest savings may cost you flexibility you need. Use the home affordability calculator to model both scenarios against your income.

Total Interest: Where the 15-Year Wins by a Wide Margin

Early in a fully amortizing mortgage, most of each payment goes toward interest because the balance is high. As principal declines, the interest portion shrinks. A shorter term accelerates this: the balance falls faster and the rate is often lower.

On the same $400,000 loan, a 30-year at 7.00% generates approximately $558,035.59 in total scheduled interest over 360 months. The 15-year at 6.25% generates approximately $217,344.46 over 180 months. That is a nominal saving of $340,691.13, assuming all payments are made on schedule and the loan is not refinanced, paid off early, or modified.

These figures exclude closing costs, taxes, insurance, discount points, and investment returns. Actual offers will differ. Keep the same principal and assumptions across scenarios so the comparison stays valid.

Total interest is not the only metric that matters. A borrower who sells or refinances in year 7 does not experience the full-term interest total. Compare cumulative cost over the period you actually expect to own the home. Run the amortization calculator to see the balance at any point.

Cash Flow Trade-Off: What the Lower Payment Buys You

The lower 30-year payment creates options. A household can direct the difference toward emergency savings, retirement contributions, other debt, home maintenance, or taxable investments. Whether those options produce wealth depends on what the household actually does with the money. A lower required payment does not create value by itself.

Take the $768.48 monthly difference from the illustrative example. A 30-year borrower who invests that amount at the end of each month at a hypothetical 7% nominal return compounded monthly would accumulate approximately $243,579.66 after 15 years. That is a mathematical illustration, not a forecast. Market returns fluctuate; fees and taxes reduce results; not every contribution gets made.

Compare that projected balance to the $340,691.13 interest saved with the 15-year. The 15-year scenario shows a larger nominal figure, but the comparison is not like-for-like: the 30-year borrower still carries a mortgage balance after year 15, while the 15-year borrower owns the home free and clear. Net-worth comparisons require accounting for the remaining balance, the invested portfolio, taxes, and risk. Ignore anyone presenting the two figures as directly equivalent.

Liquidity is a separate consideration. Money sent to a mortgage is not available for an emergency without borrowing or selling. Money held in savings can cover a repair, an income gap, or a medical bill. A borrower who commits every available dollar to a 15-year payment should have an emergency fund already in place. Use the emergency fund calculator to size the cushion before locking the term.

Break-Even, Refinance, and Which One Fits

Refinancing from a 30-year into a 15-year is not a rate comparison. It changes the rate, required payment, repayment schedule, and payoff date at once. Consider a homeowner with a $350,000 remaining balance on a 30-year at 7.00%, refinancing into a 15-year at 6.00% with $4,500 in closing costs. The 30-year payment is approximately $2,328.56. The new 15-year payment is approximately $2,953.50. The monthly cost rises by $624.94.

Dividing the closing costs by the higher payment gives roughly 7.2 months. That is not the standard refinance break-even. It measures how long the additional payments take to equal the transaction costs, not when the refinance becomes economically beneficial. A real comparison includes the existing loan's remaining schedule, the new loan's full schedule, and the date you expect to sell or refinance again.

A rate reduction alone never establishes a universal break-even period. Shortening the term can raise the required payment even when the new rate is lower. Ask for a Loan Estimate, confirm which costs are paid upfront versus rolled into the loan, and compare the proposed terms against the existing mortgage. The refinance calculator models both schedules side by side.

A 15-year fits when: the higher payment fits comfortably, income is stable, emergency savings are fully funded, retirement contributions are already funded, and debt elimination is a priority.

A 30-year fits when: the lower required payment preserves cash flow during variable income, existing obligations are significant, or liquidity matters more than interest savings. Nothing prevents extra principal payments on a 30-year — the required payment stays low and you choose when to pay more. The mortgage payoff calculator shows what extra payments do to the schedule.

Tax Treatment and DTI: Two Rules That Apply Equally

Mortgage interest is potentially deductible on both a 15-year and a 30-year loan under the same IRS rules. The deduction requires itemizing, applies to acquisition debt used to buy, build, or substantially improve the home, and is capped at $750,000 of qualifying debt for most filers. IRS Publication 936 covers the exact conditions and phase-outs. A 30-year loan generates more total interest, but that does not automatically create a larger tax benefit — the deduction never reimburses the full amount paid.

Debt-to-income ratio is part of underwriting on both loans. It compares recurring monthly debt obligations to gross monthly income. A 15-year payment is higher, which pushes DTI higher and can reduce the loan amount you qualify for. The former 43% General QM DTI ceiling was replaced with a price-based test and is not a universal current legal cutoff. Conventional underwriting guidelines can differ by program. The DTI calculator shows where you stand before you apply.

Neither tax treatment nor DTI should determine the term on its own. Compare written Loan Estimates for both structures using the same loan amount, property, and assumptions: rate, APR, points, closing costs, monthly payment, and prepayment terms.

Frequently asked questions

Sources

• Freddie Mac. "Primary Mortgage Market Survey," October 15, 2026.
• Consumer Financial Protection Bureau. "Shopping for a Mortgage."
• Consumer Financial Protection Bureau. "Ability-to-Repay and Qualified Mortgage Rule."
• Federal Reserve Bank of St. Louis. FRED series MORTGAGE30US and MORTGAGE15US.
• Internal Revenue Service. Publication 936, "Home Mortgage Interest Deduction," 2026 edition.
• U.S. Department of Housing and Urban Development. FHA Loan Limits 2026.