15-Year vs. 30-Year Mortgage Calculator
A 15-year vs. 30-year mortgage calculator helps home buyers compare monthly payments, lifetime interest costs, and long-term equity growth across the two most popular US fixed home loan terms. Discover how a 15-year loan can save you hundreds of thousands of dollars in interest—or how a 30-year loan frees up monthly cash flow for wealth building.
15-Year vs. 30-Year Mortgage Comparison
Compare monthly payments, total interest savings, equity buildup velocity, and investing opportunity costs.
Mortgage Interest Rates (Fixed APR)
15-year mortgages typically offer a 0.50% to 0.75% lower interest rate than 30-year loans.
Choosing a 15-year term cuts your lifetime interest by 60.3% and makes you mortgage-free 15 years faster.
30-Year Fixed
15-Year Fixed
Remaining Loan Balance Over Time (15 vs 30 Years)
The “Invest the Difference” Opportunity Cost Model
What happens if you take the 30-year loan and invest the $656/mo savings?
Invest $656/mo into an S&P 500 index fund at an assumed 8% annual return for 30 years:
Pay off your home in 15 years, then invest your entire $2,679/mo payment from Years 16 to 30 at 8%:
Comparative Amortization Schedule
Side-by-side annual balance reduction, interest expense, and home equity milestones.
The 15-Year Loan Pros
- • Saves 55% to 65% in lifetime interest.
- • Lower contractual APR (typically 0.5% lower).
- • Reaches 50% home equity in just 7 years.
- • Completely debt-free in 180 months.
The 30-Year Loan Pros
- • Lower mandatory monthly payment ($500-$800/mo).
- • Easier to qualify under bank DTI ratios.
- • Cash-flow safety cushion during economic downturns.
- • Option to prepay extra principal anytime.
The Opportunity Cost Factor
Paying down a 6% mortgage provides a guaranteed 6% post-tax return. However, if broad equity index funds return 8-10% historically, investing the monthly savings could yield a larger net net worth over three decades—provided you possess the discipline to invest the difference every single month.
15-Year vs. 30-Year Loan Characteristics At a Glance
Direct structural comparison of terms, payments, equity velocity, and borrowing costs.
| Feature / Metric | 15-Year Fixed Mortgage | 30-Year Fixed Mortgage |
|---|---|---|
| Monthly Payment | Higher (~30% to 35% higher) | Lower (Maximum cash-flow flexibility) |
| Total Interest Expense | Minimal (~$162,000 on $320k loan) | Heavy (~$408,000 on $320k loan) |
| Typical Interest Rate | 0.50% to 0.75% lower | Benchmark market rate |
| Equity Buildup Speed | Rapid (50% equity in ~7 years) | Gradual (50% equity in ~20 years) |
| Borrower Qualification | Requires higher verified income | Lower income needed to meet DTI caps |
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