Same house, same loan amount, one choice: 15 years or 30 years to pay it off. The term you pick changes your monthly payment and it changes how much interest you pay in total, sometimes by a lot.
The two loans, side by side
Here is an illustrative example, not a live rate quote. It uses a $320,000 loan, a fixed 6.0% rate for the 15-year term and a fixed 6.75% rate for the 30-year term. Replace both rates with your own quotes before you decide anything.
| Loan term | Illustrative rate | Monthly payment (principal and interest) | Total interest paid over the loan |
|---|---|---|---|
| 15-year | 6.0% (illustrative) | About $2,700 | About $166,000. |
| 30-year | 6.75% (illustrative) | About $2,076 | About $427,000. |
The 30-year loan’s lower monthly payment comes with a real cost: it adds up to more than double the total interest of the 15-year loan, in this example.
Why the 15-year loan usually charges less interest
Two things stack together. First, lenders often charge a lower rate for a 15-year loan than a 30-year loan on the same day, because a shorter loan is less risky for the lender to hold. Second, and this is the bigger effect, a 15-year loan simply charges interest for half as many years.
This is where amortization matters. Amortization is how a loan’s payment splits between interest and the principal, the amount you actually borrowed, over time. Early in any mortgage, most of your payment goes to interest. Later payments shift more toward principal. A 15-year loan moves through that early, interest-heavy stretch twice as fast, so it spends less total time paying interest on a large balance.
The monthly payment gap is real too
The 15-year loan is not free of tradeoffs. In this example, the monthly payment jumps from about $2,076 to about $2,700, a difference of roughly $625 a month. That is money you would need to fit into your budget every single month for 15 years straight, not just at closing.
For some buyers, that gap is the whole decision. A lender qualifies you based partly on your monthly payment against your income, so a 15-year loan can shrink how much home you qualify for, even if you could technically afford the higher payment once you own the home.
What about investing the difference instead?
This is the idea of opportunity cost, a term for what you give up by choosing one option over another. If you took the 30-year loan and its lower payment, you would have that extra $625 a month free. You could invest it instead of sending it to your lender as extra principal.
Whether that beats paying down the 15-year loan faster depends on what that money earns if invested, taxes, and how disciplined you are about actually investing it every month instead of spending it. This page is not making that call for you. It is only naming the tradeoff so you weigh it on purpose instead of by accident.
It is not always true that 15-year rates are lower
Lenders typically price 15-year loans a bit lower than 30-year loans, according to CFPB guidance on choosing a mortgage term, because the loan is repaid faster and carries less risk for the lender. But “typically” is not “always.” Rate sheets change day to day, and your own credit profile, loan size, and lender all affect the two numbers you get quoted. Ask for both quotes on the same day, at the same points, so the comparison is fair.
What this means for you
Total interest is a real number, and in a lot of cases it is a big one. But it is not the only number that matters. A 15-year loan that strains your monthly budget, leaves you with no savings cushion, or keeps you from qualifying for the home you need is not automatically the smarter choice just because it saves interest on paper.
Get real quotes for both terms from a lender. Run your own loan amount and your own two rates through the payment calculator to see your actual dollar gap, not the illustrative one used above. Then weigh that gap against your monthly budget and your other savings goals before you pick a term.