The 30-year fixed-rate mortgage is the most common loan in the United States, but the 15-year fixed is a serious alternative for borrowers who can afford the higher payment. The choice is mostly a trade-off between monthly cash flow and total interest paid.
The core trade-off
A shorter term means each payment covers more principal, so you pay the loan off faster and interest has less time to accrue. The cost is a higher monthly payment. A longer term spreads repayment over more months, lowering the payment but giving interest more time to add up.
A side-by-side example
Suppose you borrow $320,000. Compare a 15-year loan at a hypothetical 6.0% rate against a 30-year loan at a hypothetical 6.5% rate:
| Metric | 15-year @ 6.0% | 30-year @ 6.5% |
|---|---|---|
| Monthly P&I | $2,700.34 | $2,022.62 |
| Total interest | $166,062 | $408,142 |
| Total paid | $486,062 | $728,142 |
| Time to payoff | 15 years | 30 years |
The 15-year loan costs about $678 more per month but saves roughly $242,000 in interest over the life of the loan. That is the entire trade-off in one sentence: higher payments now in exchange for far less interest and a debt-free date 15 years sooner.
When a 15-year mortgage makes sense
- You can comfortably afford the higher payment and still keep an emergency fund.
- You want certainty about being debt-free by a specific age or retirement date.
- You value guaranteed interest savings over the flexibility of investing the difference elsewhere.
When a 30-year mortgage makes sense
- The lower payment fits your monthly budget and leaves room for other goals.
- You want the option to pay extra when you can, without being forced to when you cannot.
- You expect your income to grow or plan to move before 30 years.
A middle path: the 30-year with extra payments
A 30-year loan does not lock you into 30 years of interest. Because there is usually no prepayment penalty, you can make extra principal payments to mimic a 15-year schedule when cash allows, and fall back to the lower required payment when it does not. This keeps the floor low while letting you capture some interest savings. Use the Extra Payments calculator to see exactly how much time and interest a given extra payment removes.