15-Year vs 30-Year Mortgage: Which Saves You More?
A 15-year mortgage saves massive interest but costs more monthly. See the exact numbers and find out which term fits your situation.
A 15-year mortgage on a $400,000 loan at current rates saves roughly $270,000 to $300,000 in total interest compared to a 30-year mortgage. The trade-off is a significantly higher monthly payment — about $900 to $1,000 more per month. Which term is right depends on your cash flow, financial goals, and how long you plan to stay in the home.
Full Comparison: $400,000 Loan
Here is a side-by-side comparison using typical 2026 rates (15-year at 6.00%, 30-year at 6.75%):
| 15-Year (6.00%) | 30-Year (6.75%) | Difference | |
|---|---|---|---|
| Monthly P&I | $3,375 | $2,594 | $781 |
| Total payments over life | $607,500 | $933,840 | $326,340 |
| Total interest paid | $207,500 | $533,840 | $326,340 saved |
| Payoff date | April 2041 | April 2056 | 15 years sooner |
| Rate | 6.00% | 6.75% | 0.75% lower |
That is not a typo. The 30-year loan costs over $326,000 more in interest on the exact same $400,000 borrowed.
Why the Difference Is So Dramatic
Two forces compound against you on a 30-year mortgage:
- Lower rate on 15-year: Lenders offer 15-year mortgages at rates 0.50% to 0.75% lower than 30-year because they get repaid faster with less risk. That rate difference alone saves tens of thousands.
- Amortization works against 30-year borrowers: On a 30-year loan, roughly 60% of your first payment goes to interest. You do not start paying more principal than interest until around year 18. On a 15-year, you cross that threshold around year 5. More of every early payment goes to building equity.
Equity Buildup Comparison (After 5 Years)
| 15-Year | 30-Year | |
|---|---|---|
| Total payments made | $202,500 | $155,640 |
| Principal paid down | $139,400 | $38,500 |
| Remaining balance | $260,600 | $361,500 |
| Equity from payments | 34.9% | 9.6% |
After 5 years, the 15-year borrower has paid down nearly $140,000 in principal. The 30-year borrower has paid down only $38,500 — most of their payments went to interest.
When the 30-Year Makes More Sense
The 30-year mortgage is not always the wrong choice. Consider it if:
- Cash flow flexibility matters: The $781 monthly difference can fund an emergency fund, max out retirement accounts, or cover childcare costs. Financial flexibility has real value.
- You are in a high-cost-of-living area: In cities where starter homes cost $600,000+, the 15-year payment may be unaffordable without becoming house-poor.
- You plan to sell within 7-10 years: The interest savings on a 15-year accrue mostly in the second half of the loan. If you sell early, the gap narrows.
- You have higher-priority debt: Credit cards at 20%+ or student loans at 7%+ should be paid before accelerating a 6.75% mortgage.
When the 15-Year Wins Clearly
The 15-year is the better financial move if:
- The payment is under 25% of your gross income: You can absorb the higher payment without sacrificing emergency savings or retirement contributions.
- You are refinancing with significant equity: If you already have a low balance, shortening to 15 years barely changes your payment but saves enormously on interest.
- You are 40 or older and want to retire mortgage-free: A 15-year mortgage taken at 45 means you are debt-free at 60 — before most retirement ages.
- You have already maxed out retirement contributions: Once 401(k) and IRA are fully funded, rapid mortgage payoff is an excellent low-risk use of additional income.
The Opportunity Cost Argument
Some financial advisors argue for the 30-year because you can invest the $781 monthly difference. If you invest that amount at an average 8% return over 15 years:
- Invested savings: $781/month x 15 years at 8% = ~$275,000
Meanwhile, the 15-year mortgage saves $326,340 in interest. The mortgage savings wins — but only if you actually have the discipline to invest the difference every single month. Most people do not. They spend it.
The Middle Ground: 20-Year and 25-Year Terms
Some lenders offer 20-year and 25-year mortgage terms that split the difference:
| Term | Rate (est.) | Monthly P&I ($400K) | Total Interest | vs 30-Year Savings |
|---|---|---|---|---|
| 15-year | 6.00% | $3,375 | $207,500 | $326,340 |
| 20-year | 6.25% | $2,920 | $300,800 | $233,040 |
| 25-year | 6.50% | $2,702 | $410,600 | $123,240 |
| 30-year | 6.75% | $2,594 | $533,840 | — |
A 20-year term costs only $326 more per month than a 30-year but saves over $233,000 in interest. It is an excellent middle ground if the 15-year payment feels too aggressive.
Real Example: The Johnson Family
The Johnsons earn $140,000 combined and are buying a $400,000 home with 20% down ($320,000 loan):
- 15-year payment: $2,700 (23% of gross income — comfortable)
- 30-year payment: $2,075 (18% of gross income — very comfortable)
- Interest saved with 15-year: $261,000
- Monthly difference: $625
They chose the 15-year because both are 38 years old, want to be mortgage-free by 53, and have already maxed out their 401(k) contributions. The $261,000 in savings will fund several years of retirement.
Practical Takeaway
If you can comfortably afford the 15-year payment without sacrificing retirement savings or emergency funds, it is the better financial choice — you save six figures in interest and build equity three to four times faster. If the payment would stretch your budget, take the 30-year and make extra payments when you can. Use our mortgage calculator to compare both terms with your actual numbers and see the amortization charts side by side.
Try it yourself
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Open calculatorThis article is for educational purposes only and does not constitute financial advice. Consult a licensed financial advisor for decisions specific to your situation.