The total cost difference between a 15-year and 30-year mortgage is large: on a $400,000 loan, the 15-year can cut lifetime interest by more than half. The trade is a monthly payment that runs roughly a third to 40 percent higher, depending on the rates attached to each term. So the real question is which cost you would rather carry, a bigger payment now or a bigger interest bill later.
This article runs the exact numbers on a $400,000 loan, explains why the gap is so wide, and covers what the lower payment is worth if you put it to work elsewhere. It finishes with a framework for choosing the term that fits your plans, a conversation Duane Buziak has with borrowers every week.
Why Loan Term Changes Total Interest So Dramatically
Mortgages are amortized: each payment is a fixed amount that covers that month’s interest first, with the remainder reducing principal. On a 30-year loan, the early payments are mostly interest. A shorter term flips that mix sooner, because each payment has to retire the balance in half the time.
Interest accrues on whatever balance is still outstanding. A 30-year borrower carries a high balance for far longer, and that duration, more than the rate, drives most of the cost gap. Even at identical rates, the 30-year loan would cost far more in total interest because you are renting the lender’s money for twice as many years.
The rate does matter as a second effect. Shorter terms usually carry a lower rate, which widens the gap further. Freddie Mac publishes weekly averages for both terms in its Primary Mortgage Market Survey, and the 15-year average has consistently sat below the 30-year average. Check the current figures there, since they change weekly and any number quoted as of October 2026 will be out of date soon. Treat that survey as context only: your own pricing depends on credit, down payment, property and program.
One misconception is worth correcting. A 15-year payment is not double the 30-year payment, even though the term is half as long. Because the interest portion of a 30-year payment is so large, cutting the term in half raises the payment by something closer to a third, or up to about 40 percent at matching rates. That is a meaningful jump, but far smaller than most people expect.
The Total Cost Difference Between a 15-Year and 30-Year Loan on $400,000
For illustration, assume a $400,000 loan with a 15-year fixed rate of 6.0% and a 30-year fixed rate of 6.5%. These rates are illustrative, not quotes, and the figures cover principal and interest only, excluding taxes, insurance and mortgage insurance.
Monthly payment
The standard formula is payment = P × r ÷ (1 − (1 + r)−n), where r is the monthly rate and n is the number of payments.
- 15-year at 6.0%: r = 0.005, n = 180. The payment works out to about $3,375 per month.
- 30-year at 6.5%: r = 0.0054167, n = 360. The payment works out to about $2,528 per month.
Total paid and total interest
- 15-year: $3,375 × 180 = about $607,600 paid. Subtract the $400,000 borrowed, and total interest is about $207,600.
- 30-year: $2,528 × 360 = about $910,200 paid. Subtract $400,000, and total interest is about $510,200.
The deltas side by side
- Monthly payment: the 15-year is about $847 higher, roughly 34 percent more.
- Total interest: the 15-year saves about $302,600, a reduction of roughly 59 percent.
- Total paid over the life of the loan: about $607,600 versus $910,200.
In plain terms, the 15-year costs about $847 more each month and saves roughly $300,000 in interest. You also own the home free and clear 15 years sooner. Totals shift by small amounts depending on rounding and the exact rate, so run your own scenario before relying on any of these figures.
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What the Lower Payment Is Worth: Investing the Difference
The fair counterargument to the 15-year is opportunity cost. If you take the 30-year, you keep about $847 a month that the 15-year would have claimed. What that money does is the entire question.
Consider a hypothetical. Suppose you invest the $847 monthly difference for 15 years at an assumed 5% annual return. That return is an assumption for illustration, not a forecast, and your own results could be higher or lower. Compounded monthly, the account would grow to roughly $226,000. Meanwhile, on the 30-year loan, you would still owe about $290,000 at the 15-year mark. In this scenario the invested difference does not cover the remaining balance, because the loan’s 6.5% cost outruns the assumed 5% return. If you believe you can reliably earn more than your mortgage rate after taxes and risk, the math tilts the other way. Plug your own assumed return into a calculator and see where the break-even sits.
Numbers aside, liquidity matters. Home equity is hard to reach quickly: you need a sale, a HELOC or a refinance, each with its own approval and costs. Cash reserves, by contrast, handle a job loss or a roof repair immediately. A borrower who pours every spare dollar into a 15-year payment and has thin savings has traded flexibility for a faster payoff.
That is why a hybrid is popular. Take the 30-year and make voluntary extra principal payments when cash allows. You get the lower required payment as a safety net and capture part of the interest savings. Before relying on it, confirm the loan has no prepayment penalty and that extra payments are applied to principal, not held toward the next due date. The hybrid will not match a true 15-year, since the rate is typically higher, but it keeps your options open.
Which Term Fits Which Borrower: A Program and Strategy Comparison
The table below compares strategies by fit and trade-off, not by rate.
| Strategy | Best Fit For | Primary Advantage | Trade-Off to Evaluate |
|---|---|---|---|
| 15-year fixed | High, stable income; strong reserves; planning to stay long term | Lowest total interest; debt-free sooner | Highest required payment; less monthly flexibility; tighter DTI |
| 30-year fixed | Buyers prioritizing cash flow, qualification room or liquidity | Lowest required payment; easiest to qualify for | Highest total interest over the full term |
| 30-year with extra principal payments | Variable or growing income; disciplined savers | Flexibility plus partial interest savings | Savings depend on discipline; confirm no prepayment penalty |
| 20-year or other mid-term | Buyers wanting faster payoff without a full 15-year payment | Middle ground on payment and interest | Availability and pricing vary by program |
| 30-year jumbo or Non-QM/DSCR | Higher-balance buyers and real estate investors | Lower payment can protect cash flow and rental coverage | Program guidelines, reserves and pricing differ from conforming loans |
For move-up and jumbo buyers, the decision is mostly cash flow against payoff timeline. The 2026 baseline conforming limit is $806,500, and the high-cost area ceiling is $1,209,750, as published by Fannie Mae and the Federal Housing Finance Agency. Balances above your area’s limit are jumbo loans, where a 15-year payment on a large balance can become heavy fast. Many affluent buyers keep the lower payment and direct the difference toward investments or other goals.
Self-employed borrowers with variable income often value a lower required payment, since a slow quarter will not strain the budget. If your income does not fit a standard W-2 box, that is a program conversation, not a problem. Bank statement and other Non-QM programs exist for exactly this situation.
DSCR investors should pay particular attention to payment size, because coverage is typically calculated as rent divided by the full monthly housing payment. For example, imagine a property renting for $3,000 a month with a $2,500 payment: coverage is 1.2. If a shorter term pushed the payment to $3,300, coverage would fall to about 0.91, which could limit options. A longer term often helps coverage.
How Debt-to-Income and Qualification Affect Your Choice
Debt-to-income ratio, or DTI, is your monthly debt payments divided by your gross monthly income. The Consumer Financial Protection Bureau explains how DTI works, and its Owning a Home resources cover loan terms in plain language. A higher 15-year payment raises your DTI, which can reduce how much you are approved to borrow.
Here is an illustration. Suppose gross income is $10,000 a month, existing debts are $500, and you assume a 43% total DTI ceiling. That allows $4,300 in total debt, leaving $3,800 for housing. Take out $600 for property taxes and insurance, and $3,200 is available for principal and interest. At the illustrative 6.5% 30-year rate, $3,200 supports a loan of about $506,000. At the illustrative 6.0% 15-year rate, the same $3,200 supports about $379,000. That is roughly $127,000 less purchasing power. Actual DTI limits vary by program and borrower profile.
Program terms interact with this as well. FHA and VA loans offer both shorter and longer terms, and the cost of FHA mortgage insurance or the VA funding fee can vary with term, loan-to-value and borrower circumstances. Verify the current figures with your broker, since they change.
A NoTouch Credit Pull pre-qualification is a practical way to see how each term affects qualification without a hard inquiry on your credit. Duane Buziak can then model both terms side by side. Large national brands such as Rocket Mortgage and Movement Mortgage also offer both terms, so term calculators are easy to find. What a personal strategy conversation adds is how the choice fits your reserves, income and plans.
A Decision Checklist for Choosing Your Term
Five questions settle most cases. The more yes answers, the stronger the case for the 15-year:
- Does the payment fit comfortably within your budget, with room left over after other goals?
- After closing, will you hold six or more months of reserves?
- Are your retirement savings on track?
- Do you expect to stay in the home long enough to benefit from the payoff?
- Is your income stable and predictable?
Time in the home is the factor people most often underweight. In the early years of any loan, you are paying mostly interest, so a short stay captures little of the 15-year’s advantage. A long stay amplifies it, because the savings come from the later years of the schedule.
Refinancing is another path. You can start on a 30-year and refinance to a 15-year later if your income grows, but a refinance resets closing costs and your rate depends on market conditions then. Treat that as a factor to price out, not a guaranteed exit. If you are unsure, a NoTouch Credit Pull is a no-credit-impact first step toward a personalized scenario showing both terms with your numbers.
The 15-Year Wins on Cost, the 30-Year Wins on Flexibility
On the example above, the 15-year saves roughly $300,000 in interest and delivers a paid-off home 15 years sooner. The 30-year lowers the required payment by about $847 a month, improves qualification and keeps cash available for reserves, investments or surprises. Neither is the right answer in general; one fits your finances and plans better.
Stop overpaying on your mortgage, discover wholesale rates that could save you thousands over the life of your loan. Talk to Duane today for a no-obligation rate comparison with no credit impact and see exactly how much you can save with our independent mortgage expertise. Duane Buziak at Mortgage Shopping (Supra Mortgages / Duane Buziak Mortgage Maestro) can model both terms with your real numbers.
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