Choosing your mortgage term is one of the most consequential financial decisions you’ll make — and it comes down to a single trade-off: monthly affordability versus lifetime cost. Let me put real numbers on both sides, then help you pick.
The headline difference
Here’s a $300,000 loan priced both ways. The 15-year payment is higher, but watch the interest column:
| 30-year | 15-year | |
|---|---|---|
| Rate (typical gap) | 6.50% | 5.75% |
| Monthly payment (P&I) | $1,896 | $2,491 |
| Total interest | ~$382,600 | ~$148,400 |
| Interest saved | — | ~$234,200 |
That saving isn’t a rounding error — it’s a second car, a college fund, or several years of retirement savings. Two forces create it: a 15-year fixed-rate mortgage is repaid in half the time, and it almost always carries a lower rate because the lender’s risk is smaller.
When the 30-year wins
A longer term isn’t “the worse choice.” It’s the right choice when:
- Cash flow is tight. The ~$595/mo lower payment leaves room for emergencies, childcare, or breathing space.
- You can out-invest the rate. If your rate is modest and you reliably invest the monthly difference, the math can favor the 30-year.
- You value flexibility. You can always pay a 30-year like a 15-year by adding extra principal — but you can never force a 15-year to be cheaper in a hard month.
The 30-year mortgage with disciplined extra payments gives you the best of both worlds: a low required payment and a fast actual payoff. See how to pay off your mortgage early.
When the 15-year wins
Choose the shorter term when:
- You have stable, comfortable income and the higher payment still leaves a healthy savings rate.
- You want to be debt-free before a milestone like retirement or college.
- You value the faster equity and the lower rate, and won’t miss the cash-flow flexibility.
Run your own numbers
Averages are a starting point, not an answer. Plug your loan amount, rate and term into the mortgage calculator, then add an extra monthly payment to a 30-year scenario with the mortgage payoff calculator and watch the interest savings and payoff date move. For the full picture — affordability, PMI, refinancing — see the complete mortgage guide.
