15-Year vs 30-Year Mortgage Calculator
Compare monthly payments, total interest, equity building speed, and the opportunity cost of each mortgage term side by side.
Opportunity Cost Analysis
What if you took the 30-year loan and invested the monthly savings of $625/mo?
| Year | 15-Year Strategy (Equity) | 30-Year Equity | Investment Balance | 30-Year Total Wealth | Difference |
|---|---|---|---|---|---|
| 5 | $111,701 | $55,125 | $44,730 | $99,855 | $-11,846 |
| 10 | $213,880 | $82,955 | $108,139 | $191,095 | $-22,785 |
| 15 | $350,000 | $121,439 | $198,031 | $319,470 | $-30,530 |
| 20 | $350,000 | $174,654 | $325,463 | $500,118 | +$150,118 |
| 25 | $350,000 | $248,242 | $506,115 | $754,356 | +$404,356 |
| 30 | $350,000 | $350,000 | $762,210 | $1,112,210 | +$762,210 |
Which Is Right for You?
- You have a stable, high income
- You're close to retirement and want to be mortgage-free
- You have no other high-interest debt
- You have a solid emergency fund (6+ months)
- You want guaranteed interest savings
- You want lower required monthly payments
- You have other high-interest debt to pay off first
- You want flexibility to invest the savings
- Your budget is tight or income is variable
- You plan to make extra payments when possible
15-Year vs 30-Year Mortgage: Complete Guide
The choice between a 15-year and 30-year mortgage is one of the most impactful financial decisions a homebuyer makes. The difference goes far beyond monthly payments — it affects your total cost of homeownership, how quickly you build equity, your cash flow flexibility, and even your long-term investment strategy. Understanding the math behind each option helps you make a confident choice.
How Rate Differences Compound the Savings
Fifteen-year mortgage rates are typically 0.50% to 0.75% lower than 30-year rates. This isn't just a small perk — it compounds dramatically. You're paying a lower rate on a loan that also amortizes in half the time. The combination means you pay far less interest overall. In many cases, the total interest on a 30-year mortgage is three to four times what you'd pay on a 15-year, even though the loan amount is identical.
The Cash Flow Argument for 30-Year Mortgages
While 15-year mortgages save a remarkable amount of interest, the 30-year mortgage offers something equally valuable: flexibility. The lower required payment means more room in your monthly budget for emergencies, retirement contributions, college savings, or simply peace of mind. Life is unpredictable — job changes, medical expenses, and economic downturns happen. With a 30-year mortgage, you can always choose to pay extra, but you're never forced to.
The Investment Alternative
One of the strongest arguments for the 30-year mortgage is the opportunity cost of tying up extra cash in your home. If you take the 30-year mortgage and invest the monthly savings in a diversified portfolio averaging 7% annual returns, the investment growth can offset — and sometimes exceed — the interest savings of the 15-year option. This is especially true when mortgage rates are low relative to expected investment returns. The Opportunity Cost Analysis above models this scenario with your specific numbers.
Tax Implications
The mortgage interest deduction allows homeowners to deduct interest paid from their taxable income. With a 30-year mortgage, you pay more interest, which means a larger potential deduction. However, since the 2017 Tax Cuts and Jobs Act nearly doubled the standard deduction, far fewer homeowners itemize their returns. For most buyers, especially those with smaller mortgages, the tax benefit is negligible and should not drive your term decision. Focus on total cost and cash flow instead.
When Each Option Makes the Most Sense
The 15-year mortgage is strongest for borrowers who are approaching retirement and want to eliminate housing costs, have high and stable income with no other significant debts, or simply want the guaranteed return of paying less interest. It's also ideal for those who struggle with the discipline of voluntary extra payments — the higher required payment forces accelerated payoff.
The 30-year mortgage makes the most sense for first-time buyers stretching to afford a home, households with variable income, borrowers who have higher-interest debt to prioritize, and disciplined investors who will actually invest the monthly savings rather than spending them. Many financial professionals recommend the 30-year with a commitment to pay extra when possible — this gives you the safety net of a lower required payment while still building equity quickly.