15-Year vs 30-Year Mortgage: Which Actually Costs Less

A 30-year term lowers your monthly payment, but the total cost of the mortgage almost always goes up sharply — here's exactly how much.

Choosing a longer mortgage term is one of the easiest ways to make a monthly payment look more manageable, which is exactly why the 30-year mortgage dominates US home lending. It's also one of the easiest ways to quietly increase what you pay in total, often by well over a hundred thousand dollars, without changing the amount you borrowed or the rate you're charged.

Why a longer term costs more even at the same rate

Interest accrues on your remaining balance every month. The longer that balance takes to shrink, the more months of interest accumulate on top of it. Stretching the term doesn't just spread the same total cost over more payments — it increases the total cost, because your balance stays higher for longer, and mortgage balances are large enough that this effect compounds dramatically over 30 years.

A side-by-side example

Take a $320,000 mortgage at a 6.5% rate. Over 30 years, the principal-and-interest payment is about $2,022 a month, and total interest paid over the life of the loan comes to roughly $407,900. Shorten that to 15 years and the payment rises to about $2,788 — a meaningful monthly increase — but total interest drops to around $181,900. That's over $225,000 less paid in interest alone, for borrowing the exact same amount at a comparable rate (15-year mortgages also typically carry a somewhat lower rate than 30-year loans, which widens the gap further). Run your own numbers through our payment breakdown calculator to see this play out with your actual figures.

Where this tradeoff shows up most sharply

Refinancing, where switching from a 30-year to a 15-year term partway through can dramatically cut remaining interest
First-time buyers who default to a 30-year term without comparing the total-cost gap
Move-up buyers who could afford a 15-year payment but haven't run the comparison

It isn't always the wrong choice

A 30-year term can be the right call when the monthly payment relief solves a real cash flow problem, or frees up money for other financial goals like retirement savings or an emergency fund. Most US mortgages don't penalize early payoff, so a 30-year stated term with a plan to pay extra toward principal can combine flexibility with a lower forced monthly obligation. The mistake is choosing the longer term purely because the payment on the page looks smaller, without ever calculating the total cost.

The trap of payment-only comparison

Because listings and lenders often lead with the monthly payment, it's easy to compare two mortgage options on payment alone and pick the one that feels easier — without realizing you're comparing a 15-year loan to a 30-year one. Always compare total interest over the full term, and if you're weighing loans of different lengths, that comparison is close to meaningless unless you look at total cost too.

How this connects to refinancing

If you're several years into a 30-year mortgage and your financial situation has improved, refinancing into a 15-year term can sometimes lower your total remaining cost even if the monthly payment rises. Our guide on the arithmetic of refinancing a mortgage walks through how to check whether that trade is worth it in your specific case.

Key takeaway A 30-year term lowers the monthly payment but almost always raises total interest paid by well over a hundred thousand dollars compared to a 15-year term — always compare mortgages of different lengths by total cost, not payment size.

A middle path: extra principal payments on a 30-year loan

You don't have to choose the higher required payment of a 15-year loan to capture some of its benefit. Making extra principal payments on a 30-year mortgage, even irregularly, shortens the effective payoff timeline and cuts total interest, while preserving the flexibility of the lower required payment during months when cash is tighter. The tradeoff is that this discipline has to be maintained voluntarily, whereas a 15-year term builds the faster payoff into the required payment itself.

A rule of thumb worth applying

A useful discipline is running both the 15-year and 30-year-with-extra-payments scenarios through the payment calculator side by side, using a realistic extra payment amount you could sustain, before assuming either term is automatically the better choice for your situation.

Term length and building equity

A shorter term builds home equity meaningfully faster, both because more of each payment goes to principal and because the loan itself amortizes over fewer years. This matters if you expect to sell within a decade, since a 15-year mortgage will have paid down substantially more principal than a 30-year loan over the same holding period, directly affecting how much cash you walk away with at sale.

A simple gut check before choosing a term

Ask what the total interest is at each term length, not just the monthly payment
Decide whether the monthly difference between the two terms is actually needed for your budget, or just feels more comfortable
Consider whether a 30-year term with a plan for extra payments achieves a similar result with more flexibility

The psychological pull of a lower number

A payment that's several hundred dollars lower each month feels like an easy win in the moment, which is exactly why 30-year terms are the default in US mortgage marketing. The total interest gap, spread out in small monthly increments over three decades, doesn't feel as real as a single upfront number would. Seeing the total cost side by side, the way our calculator displays it, is often the only thing that makes the tradeoff feel concrete enough to weigh properly before signing.

Comparing across loan types, not just term lengths

The same logic that applies to 15-year versus 30-year terms applies when comparing a fixed-rate mortgage against an ARM for the same purchase, or a conventional loan against an FHA loan. Whenever you're choosing between two different financing structures for the same home, put both through the total-cost lens rather than defaulting to whichever one has the friendlier-looking monthly number.

Term length and refinancing flexibility later

Choosing a shorter term now doesn't lock you out of flexibility later — if your circumstances change, most US mortgages without prepayment penalties allow you to make extra payments voluntarily, effectively shortening the term further. What a longer term does lock in, unless you refinance or pay extra, is the higher total interest baked into the schedule from day one, which is the core reason it deserves more scrutiny than the payment line alone provides.

A final way to frame the decision

Think of the gap between a 15-year and 30-year term not as a fee you're avoiding, but as a price you're paying for flexibility in your monthly budget. Framed that way, it becomes a legitimate tradeoff to weigh deliberately, rather than a default you fall into because the payment line happened to look smaller.

What to do next

Take the price and down payment you're considering and run both a 15-year and 30-year term through the payment breakdown calculator so you're comparing total cost, not just the number that shows up on the payment line.

This content is general information, not personalized financial advice — your specific situation may differ.