15 vs 30-Year Mortgage Calculator
Compare a 15-year and 30-year mortgage side by side to see which makes sense for your situation. Enter your loan amount, the interest rate for each term and the calculator instantly displays monthly payments, total interest paid, total cost, and total interest savings. You will see that a 15-year mortgage typically has a higher monthly payment but much lower interest rate and significantly less total cost. The calculator also shows the extra monthly cost of choosing the 15-year option and helps you understand when the 15-year loan breaks even in cumulative savings. Use this to weigh the benefits of paying off your mortgage faster against the flexibility of lower 30-year payments, and model how you could achieve similar payoff using extra principal payments on a 30-year loan.
On a $320,000 loan, the 15-year mortgage (at 6.00%) costs --/mo while the 30-year (at 6.75%) costs --/mo. The 15-year saves -- in total interest.
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How the comparison is calculated
Both loans use the standard PMT (payment) amortization formula described by the CFPB in Understand Loan Options. The 15-year and 30-year payments are computed independently using their respective rates, then compared. Total interest is total payments minus principal for each term.
r = annual rate / 100 / 12
n = term years x 12
monthly payment = loan x r x (1 + r)^n / ((1 + r)^n - 1)
total interest = (monthly payment x n) - loan
Worked example
$320,000 loan, 30yr at 6.75%, 15yr at 6.00%:
- 30yr: r = 6.75/100/12 = 0.005625, n = 360. Monthly = $320,000 x 0.005625 x (1.005625)^360 / ((1.005625)^360 - 1) = $2,076.94. Total interest = $747,699 - $320,000 = $427,699.
- 15yr: r = 6.00/100/12 = 0.005, n = 180. Monthly = $320,000 x 0.005 x (1.005)^180 / ((1.005)^180 - 1) = $2,701.37. Total interest = $486,247 - $320,000 = $166,247.
- Interest savings = $427,699 - $166,247 = $261,452
- Extra monthly cost = $2,701.37 - $2,076.94 = $624.43
Understanding the tradeoff
The bar chart in the results shows total interest as a percentage of the original loan amount. On a typical 30-year mortgage at current rates, total interest can exceed 100% of the principal, meaning you pay more than double the loan amount over the life of the loan. A 15-year mortgage at a lower rate dramatically reduces this multiple.
The break-even analysis compares the cumulative extra monthly payments required by the 15-year loan against the cumulative interest savings achieved by the shorter term. Because you save interest over every remaining month of the 30-year loan after the 15-year loan would have been paid off, the 15-year mortgage always delivers a net benefit for borrowers who hold the loan to maturity and can afford the higher payment.
The practical question is whether the monthly payment difference strains your budget. A useful test: if the higher 15-year payment would require you to carry other high-interest debt (credit cards, personal loans), the 30-year mortgage with targeted debt payoff may be the better path. The CFPB provides a broader framework for evaluating affordability at consumerfinance.gov/owning-a-home.
Rate difference: why 15-year is usually cheaper
Lenders price shorter-term loans lower because their duration risk is lower. The default spread between 15-year and 30-year fixed rates is typically between 0.5 and 1.0 percentage points, though it varies with market conditions. This rate difference amplifies the interest savings of the 15-year option: you pay off the loan in half the time and at a lower rate, compounding the benefit.
If you are shopping for a mortgage, use the rate inputs in this calculator to model the actual rates you are quoted, rather than the defaults. Even a small rate difference has a large effect on total interest for a 30-year loan.
15 vs 30-year mortgage: frequently asked questions
Should I choose a 15-year or 30-year mortgage?
The answer depends on your monthly cash flow, job security, and financial goals. A 15-year mortgage saves a large amount of interest and builds equity faster, but requires higher monthly payments. A 30-year mortgage offers lower monthly payments, giving you more flexibility to invest the difference elsewhere or handle unexpected expenses. If the higher 15-year payment would strain your budget, the 30-year option may be more prudent. Use this calculator to compare the exact numbers for your loan.
Is a 15-year mortgage always better financially?
Not necessarily. A 15-year mortgage pays less total interest, but the opportunity cost matters. If the extra monthly payment you would make on a 15-year loan could be invested in assets earning a higher return than your mortgage interest rate (after the mortgage interest deduction, if applicable), the 30-year mortgage might yield better overall wealth accumulation. This is a personal finance tradeoff that depends on your tax situation, risk tolerance, and investment options. The CFPB's owning-a-home resources at consumerfinance.gov provide further guidance.
Why are 15-year mortgage rates lower than 30-year rates?
Lenders face less risk on a 15-year loan because the repayment period is shorter, reducing the chance of borrower default or market changes over the loan's life. The shorter duration also means investors in mortgage-backed securities require a smaller risk premium. As a result, lenders can offer lower rates on 15-year mortgages, typically 0.5 to 1.0 percentage points below 30-year rates, though the spread varies with market conditions.
What if I take a 30-year mortgage but make extra principal payments?
Making extra principal payments on a 30-year mortgage reduces the outstanding balance faster, which shortens the effective loan term and reduces total interest paid. This approach gives you the flexibility of the lower required payment while letting you accelerate payoff when finances allow. However, unlike a 15-year mortgage, there is no contractual obligation to make the larger payments, which requires discipline. Some borrowers prefer this flexibility; others prefer the forced savings of a shorter term.
What is the break-even point between a 15-year and 30-year mortgage?
The break-even point compares the extra monthly cost of a 15-year mortgage against the total interest savings. You pay more each month on the 15-year loan, but you save a large amount of total interest. The break-even in this calculator shows how many years it takes for the cumulative interest savings to exceed the cumulative extra payments made. Because the interest savings compound over time while the extra payments are linear, the 15-year mortgage almost always comes out ahead for borrowers who can afford the payment.
How do I compare rates when shopping between 15 and 30-year loans?
Ask lenders for the APR (annual percentage rate) for each term, not just the interest rate. The APR includes fees and closing costs, making it a more accurate basis for comparison. The CFPB's loan estimate form, which lenders are required to provide within three business days of application, shows the APR, monthly payment, and total payments for each loan option so you can compare on a like-for-like basis.
Official sources
- Mortgage types and payment calculations: CFPB, Owning a Home.
- Loan options comparison: CFPB, Understand Loan Options.
Reviewed by the CalculatorHub team, edited by James Graham, 12 June 2026. See our methodology. General information only, not financial advice.