15-Year vs 30-Year Mortgage

By Muhammad Asad · Last updated: 2026-10-01

On a $320,000 loan at 6.5%, a 15-year mortgage costs $764.93 more per month than a 30-year — but saves $226,384.52 in total interest and gets you debt-free 15 years sooner. That's the whole trade in one sentence: monthly breathing room versus lifetime cost. Here's the full math so you can pick with your eyes open.

The numbers, side by side

Same $320,000 loan, same 6.5% rate, two different terms. Every figure below comes from the standard amortization math our calculators use:

30-year: $2,022.62/month principal & interest → $408,142.36 total interest → $728,142.36 paid over 360 months.
15-year: $2,787.54/month principal & interest → $181,757.84 total interest → $501,757.84 paid over 180 months.
Difference: the 15-year costs $764.93 more per month (about 38% higher) and saves $226,384.52 in interest.

Read that savings number again: over two hundred thousand dollars. It's more than half the loan amount, and it's the single biggest lever in the entire homebuying decision. Our mortgage calculator lets you flip between terms on your own numbers — the interest gap is always bigger than people expect.

Why the gap is so enormous

Two forces combine. The obvious one is time: the 30-year borrower pays interest on a balance for twice as many years, and in the early years that balance barely shrinks — after 5 years of minimum payments, the 30-year borrower still owes $299,555 of the original $320,000.

The second force is the rate spread: in the real market, 15-year rates usually sit about 0.5 to 0.75 percentage points below 30-year rates (per Freddie Mac's mortgage survey), because the lender's capital is at risk for half as long. The comparison above deliberately uses the same 6.5% rate for both terms, so the $226,385 savings you see is the pure effect of the shorter term. With the typical rate discount, the real-world savings would be even larger.

Equity: the hidden scoreboard

Total interest gets the headlines, but equity is what changes your life. After 5 years of payments on that $320,000 loan:

15-year: balance $245,494.78 → you've paid down $74,505.22 of principal.
30-year: balance $299,555.13 → you've paid down $20,444.87 of principal.
The 15-year borrower has nearly 3.6× the equity from payments alone — before any appreciation. That's the difference between being able to sell, refinance, or tap equity in year 5 and still owing almost the entire loan.

Fast equity also matters for PMI: if you put down less than 20%, the 15-year schedule gets you to the 80% cancellation threshold years sooner (see our PMI guide for the mechanics).

The qualifying hurdle

Here's the catch that keeps most buyers on 30-year loans: the 15-year payment is roughly 38% higher, and lenders judge it against the same debt-to-income limits. A $2,787.54 payment needs about $9,956 of gross monthly income to stay within the 28% front-end rule — versus $7,224 for the $2,022.62 payment.

Qualification requirements (credit score minimums, down payment rules, DTI caps) are identical for both terms. The practical constraint is purely income: at the same loan amount, the 15-year demands a meaningfully bigger paycheck to pass underwriting. That's why only about 15% of borrowers take 15-year loans, per industry data — not because the math is bad, but because the payment is steep.

The 20-year compromise

Stuck between the two? The 20-year fixed is the option nobody talks about. On the same $320,000 loan at 6.5%:

20-year: $2,385.83/month → $252,600.17 total interest over 240 months.
That's $363.21 more per month than the 30-year, but $155,542.19 less in total interest — you capture more than two-thirds of the 15-year's savings for less than half of its monthly premium.

If the 15-year payment breaks your budget but the 30-year's interest bill makes you queasy, price the 20-year before deciding. Some lenders also offer it at a small rate discount versus the 30-year.

The flexibility play: 30-year loan, 15-year payoff

There's a third path that gets you almost all of the 15-year's savings with none of its rigidity: take the 30-year, then voluntarily pay extra principal equal to the payment difference. The math checks out exactly:

Add $764.93/month in extra principal to the $320,000, 6.5%, 30-year loan and it pays off in 180 months — 15.0 years flat — with $181,757.34 in total interest. That's within pennies of the actual 15-year loan's $181,757.84. But in any month where cash is tight — a job loss, a medical bill — you can drop back to the required $2,022.62 with no penalty and no refinance.

The trade-off is discipline: the savings only materialize if you actually make the extra payments, every month, for 15 years. Automate it as a recurring extra-principal payment so willpower isn't part of the plan. And note this works because we compared at the same rate — in reality the 15-year's rate discount means a true 15-year loan still wins by a bit on interest.

Which should you choose?

Take the 15-year if the higher payment still keeps housing comfortably under ~28% of gross income, you have a solid emergency fund, and you're on track with retirement savings. You'll save six figures in interest, guaranteed.
Take the 30-year if the 15-year payment would strain your budget, you carry higher-interest debt to kill first, you're behind on retirement and need the cash flow, or your income is variable. Flexibility you actually use beats savings you can't afford.
Take the 30-year and pay extra if you want the 15-year's economics with an escape hatch — but only if you'll automate the extras and treat the higher payment as mandatory.
Consider the 20-year if you want most of the savings without the full payment shock.

One more consideration: if you won't stay in the home long — say under 7–10 years — the term matters less than you think, because you'll sell before most of the interest savings accrue. Match the loan to your horizon, not just your budget.

Run both on your numbers

Open our mortgage calculator, enter your price, down payment, and rate, then flip the term between 15, 20, and 30 years — it shows the payment, total interest, and full amortization schedule for each. Pair it with our affordability calculator to check which term's payment your income actually supports under the 28/36 rule.

Assumptions and limits

All figures on this page are for 2026, using a fixed 6.5% rate for both terms and the standard amortization formula. Real-world 15-year rates typically run 0.5–0.75 points below 30-year rates, which would widen the savings shown here. Extra-payment examples assume no prepayment penalty (verify with your lender) and extras applied to principal. These are planning estimates, not financial advice — your rate, taxes, insurance, and how long you'll keep the loan all change the answer.

Frequently asked questions

How much do you save with a 15-year mortgage?

On a $320,000 loan at 6.5%, the 15-year saves $226,384.52 in total interest versus the 30-year ($181,757.84 vs $408,142.36). The catch: the 15-year payment is $2,787.54 a month, $764.93 more than the 30-year's $2,022.62.

Is the 15-year mortgage rate lower than the 30-year?

Usually, yes. Fifteen-year rates typically run about 0.5 to 0.75 percentage points below 30-year rates because the lender's money is at risk for half the time. The comparison on this page uses the same 6.5% rate for both so you're seeing the pure effect of the shorter term.

Can I pay off a 30-year mortgage like a 15-year?

Yes, if your loan has no prepayment penalty (most don't). Adding $764.93 a month in extra principal to a $320,000, 6.5%, 30-year loan pays it off in exactly 180 months with $181,757.34 in total interest — effectively identical to the 15-year, with the option to drop back to the lower payment in a tight month.

Is a 15-year mortgage harder to qualify for?

In practice, yes. Qualification rules are the same, but the 15-year payment is roughly 38% higher, so it eats more of your debt-to-income allowance. The same income that qualifies for a $320,000 loan on a 30-year term may only qualify for a smaller loan on a 15-year term.

What about a 20-year mortgage?

It's the underrated middle ground. On that same $320,000 loan at 6.5%, a 20-year fixed costs $2,385.83 a month with $252,600.17 in total interest — about $155,500 less interest than the 30-year for $363 more a month.

Should I take the 30-year and invest the difference?

That's the classic counterargument: if you can reliably earn more investing than your mortgage rate costs you, the 30-year plus investing can win on paper. It demands real discipline — actually investing the difference every month for decades — plus tolerance for market swings. Most people do better with the guaranteed savings of the shorter term.

Does a 15-year mortgage build equity faster?

Dramatically. After 5 years on a $320,000 loan at 6.5%, the 15-year borrower has paid down $74,505 of principal versus $20,445 on the 30-year. That's the difference between having real equity to tap or sell from, and still owing nearly the whole loan.