15 vs 30-year mortgage: the definitive comparison

The 15-versus-30-year mortgage debate is one of the few in personal finance where both camps are right — about different people. The 15-year loan is a forced-savings machine with a cheaper rate; the 30-year is a flexibility machine with a bigger interest bill and better options attached. Here's the full worked comparison at today's approximate rates, the honest case for each, and the hybrid play most people never consider.

The numbers, worked

Assume a $350,000 loan. As of early 2026, 30-year fixed rates hover around 6.3% and 15-year rates around 5.6% — 15-year money is almost always 0.5–0.75 points cheaper because lenders take less duration risk. All figures below are labeled estimates; your quote will differ.

The case for the 15-year

• A meaningfully lower rate — the only free lunch in the comparison. Same borrower, cheaper money.
• Forced discipline: the equity builds whether or not you're the type to invest a monthly surplus (most people aren't — the 'I'll invest the difference' plan usually becomes dinner).
• A paid-off house before college bills or retirement, which transforms cash-flow math in your 50s.
• Equity builds roughly 4x faster in the early years, which matters if you might move or need to borrow against the home.

The case for the 30-year

• Flexibility is insurance: the lower required payment is what you owe when life goes wrong — job loss, illness, divorce. You can always pay more; you can never pay less.
• The spread math: if your mortgage costs ~6.3% and long-run stock returns average 7–10%, the extra $710/month may build more wealth in an index fund — especially inside tax-advantaged accounts.
• Priority ordering: $710/month should usually fill a 401(k) match, Roth IRA, and HSA before it prepays a middle-single-digit mortgage.
• Inflation quietly shrinks a fixed payment: $2,166 in 2046 will feel dramatically smaller than it does today.

The tiebreakers

The hybrid: take the 30, pay it like a 15

Take the 30-year loan, then voluntarily send the 15-year-sized payment each month, with the extra earmarked to principal. You give up the 15-year's lower rate — that part is a real cost — but you keep the option to drop back to the smaller required payment the month anything goes wrong. You're buying insurance with the rate spread. For households with variable income or thin margins who still want the payoff arc, it's frequently the best answer on the board.

1. 1
   Confirm extra payments are penalty-free

   Nearly all conforming US loans allow unlimited prepayment; verify before closing anyway.

2. 2
   Automate the extra principal

   A recurring extra payment flagged 'apply to principal' — unflagged extras sometimes get held as prepaid interest.

3. 3
   Check the application annually

   Confirm your servicer applied extras to principal. Errors are common and fixable.

4. 4
   Downshift without guilt when needed

   The whole point of the structure is that the smaller payment is always legally sufficient.

The bottom line

The 15-year wins on rate and discipline; the 30-year wins on flexibility and opportunity cost — and the gap between them is smaller than the $262,000 headline suggests once you account for what the monthly difference could earn elsewhere. If you're maxing retirement accounts and want the house gone, take the 15. If you're still building, take the 30 and put the difference where the tax code pays you to put it. And if you want both discipline and an escape hatch, take the 30 and pay it like a 15 — the option to stop is worth more than the rate spread costs.