15-Year vs. 30-Year Mortgage: The Total Interest Trade-Off
The 30-year mortgage won by default for most buyers, mostly because the payment is lower and lower payments qualify more people for more house. That's a legitimate reason to choose one — but "the payment is lower" and "the loan is cheaper" are two different claims, and the 15-year term wins the second one by an amount most buyers never actually see spelled out. Run both terms against your own numbers in our Mortgage Amortization Calculator.
On our $300,000 home with 10% down ($270,000 loan), a 30-year fixed at 6.66% runs about $1,735/month; a 15-year fixed at 6.04% runs about $2,284/month — $549 more each month. In exchange for that higher payment, the 15-year loan pays off in half the time and costs about $141,200 in total interest instead of roughly $354,600 for the 30-year — a difference of about $213,400. The lower rate on top of the shorter term is doing real work in that gap, not just the faster payoff schedule alone. See your own numbers in our Home Affordability Calculator.
The monthly payment difference
| Term | Rate | Monthly payment (P&I) | Difference from 30-yr. |
|---|---|---|---|
| 30-year | 6.66% | $1,735 | — |
| 15-year | 6.04% | $2,284 | +$549/month |
That $549 gap is the entire decision for most households — it's the number that has to fit comfortably in a monthly budget, alongside taxes, insurance, and everything else, for the 15-year term to even be on the table. Stress-test it against your real monthly numbers in our Budget Calculator before assuming it fits.
Total interest paid over the life of each loan
| Term | Total paid over full term | Total interest paid |
|---|---|---|
| 30-year | $624,600 | $354,600 |
| 15-year | $411,200 | $141,200 |
The 30-year loan costs more than the entire original loan amount again in interest alone — $354,600 in interest on a $270,000 loan. The 15-year loan's interest bill is barely half the loan amount. Two things compound to create that gap: a lower rate on the 15-year term, and a much shorter window for interest to accrue at all — the loan simply doesn't exist long enough to rack up decades of compounding on a large remaining balance.
How rates typically differ between 15- and 30-year terms
Lenders price 15-year loans lower because they carry less risk over a shorter horizon — less time for the borrower's situation or the broader economy to change, and less time for the lender's money to be tied up at a fixed rate if market rates rise. Freddie Mac's most recent survey puts 30-year fixed loans at 6.71% and 15-year fixed loans at 6.04%, a spread of roughly 0.67 percentage points; the spread commonly runs somewhere between 0.5 and 0.75 points depending on the broader rate environment, though it can narrow or widen with market conditions. That spread is a real, compounding part of the total-interest gap above — it's not just the shorter term doing the work.
How much home equity you'd actually build
The interest totals above play out over the full loan, but the equity difference shows up much sooner than that — this is principal paid down through the loan itself, before any home-price appreciation, which applies equally to both terms and isn't part of this comparison:
| Term | Balance after 5 yrs. | Balance after 10 yrs. | Principal paid off by year 10 |
|---|---|---|---|
| 30-year | $253,219 | $229,795 | $40,205 |
| 15-year | $205,380 | $118,035 | $151,965 |
By year 10, the 15-year borrower has paid down almost four times as much principal as the 30-year borrower on the identical original loan amount — a real, practical difference if you'd ever need to sell, refinance, or borrow against home equity within that window. The 30-year loan's early payments are still overwhelmingly interest; the 15-year loan reaches meaningful equity far faster simply by design.
The opportunity-cost question
The $549/month difference doesn't have to go toward extra mortgage principal — it could just as easily go into a retirement account or other investment instead, and that comparison is worth being honest about rather than assuming the mortgage always wins. Paying down the 15-year loan guarantees a return equal to its 6.04% rate, since every dollar of interest not paid is a dollar kept. Investing that $549/month elsewhere carries market risk and no guaranteed return, but has historically outperformed 6% over long holding periods in broad stock market indexes — with no guarantee that holds over any specific 15-year stretch. Neither answer is universally correct: a guaranteed 6.04% is a genuinely strong, risk-free return in its own right, and a household uncomfortable with market risk on money tied to their home may reasonably prefer the certainty. This isn't investment advice — a fee-only financial advisor can help weigh it against your specific retirement timeline and risk tolerance.
The middle ground: paying a 30-year loan like a 15-year one
You don't have to choose between the two payments in isolation. Taking the 30-year loan at 6.66% but voluntarily paying the 15-year-equivalent amount — $2,284/month, applying the extra $549 directly to principal — pays off the loan in about 16 years instead of 15, and costs roughly $170,900 in total interest instead of $141,200. That's about $28,000 more in interest than a true 15-year loan, because you're still paying the higher 30-year rate on every dollar of remaining balance. But it still saves roughly $183,700 versus making only the required 30-year payment — and unlike a real 15-year loan, nothing obligates you to keep paying the higher amount. In a month where money is tight, you can drop back to the required $1,735 payment with no penalty, no missed payment, and no call to your lender.
This is the flexibility a true 15-year loan doesn't offer: its higher payment is contractually required every month, whether or not that month is a good one. Model your own extra-payment scenario in our Mortgage Amortization Calculator to see your specific payoff date and interest total.
Who a 15-year term realistically fits — and who it doesn't
- Fits: stable, comfortably-above-the-minimum income where the extra $549/month doesn't crowd out retirement savings or an emergency fund; buyers prioritizing being mortgage-free by a specific date (retirement, a child's college years); anyone who already has 3–6 months of expenses saved and isn't relying on this home purchase to stretch their budget to its limit.
- Doesn't fit: first-time buyers already near their maximum qualifying payment; anyone without a solid emergency fund, since a contractually higher payment reduces the room to absorb a job loss or emergency; buyers who could reasonably expect to earn more investing the $549/month difference elsewhere than the 6.04% they'd save in mortgage interest, especially in a tax-advantaged retirement account; and anyone who values flexibility more than certainty — the extra-payment middle ground above captures most of the benefit without giving that flexibility up.
Worksheet: compare both terms on your own numbers
| Step | What to calculate | 30-year | 15-year |
|---|---|---|---|
| 1 | Your quoted rate | _______% | _______% |
| 2 | Loan amount | $_______ | $_______ |
| 3 | Monthly payment (P&I) | $_______ | $_______ |
| 4 | Difference from 30-yr. payment (Step 3 − 30-yr. Step 3) | — | $_______ |
| 5 | Total interest over full term | $_______ | $_______ |
| 6 | Interest saved by choosing 15-year (30-yr. Step 5 − 15-yr. Step 5) | $_______ |
Get exact figures for your own rate and loan amount, including the extra-payment middle-ground scenario, in our Mortgage Amortization Calculator.
Frequently asked questions
Can I switch from a 30-year to a 15-year loan later?
Yes, through a refinance — you'd requalify at that point, pay new closing costs, and take whatever 15-year rate is available at that time, which may be higher or lower than today's. The extra-payment strategy above achieves a similar result without a refinance, new closing costs, or the risk of qualifying at a worse rate later.
Does a 15-year loan mean less total PMI if I put down less than 20%?
Often yes — PMI typically cancels once you reach 20% equity, and a 15-year loan builds equity faster on the same starting balance, both from higher scheduled principal payments and (usually) faster price appreciation exposure over a shorter horizon. That can mean fewer total months of PMI payments even though the monthly payment itself is higher.
Is a 20-year mortgage a reasonable middle ground instead?
It's a real option where lenders offer it, sitting between the two in payment, total interest, and typically also in rate. It's less universally available than 15- and 30-year terms, so availability and pricing are worth checking directly with a lender rather than assuming it's offered.
Should I always pay extra toward a 30-year loan if I can afford to?
Usually reasonable, but check for a prepayment penalty first (rare on conventional loans today, but worth confirming) and weigh it against other uses for the same money — an employer retirement match, high-interest debt, or an emergency fund that doesn't yet cover 3–6 months of expenses typically come first, since a mortgage is usually the lowest-rate debt most people carry.
Do 15-year loans have different qualification requirements?
The underwriting criteria (credit, income, debt-to-income ratio) are generally the same, but the higher monthly payment itself is what typically makes qualifying harder — a 15-year loan's payment counts more heavily against your debt-to-income ratio than the same loan amount at 30 years, which can lower the maximum home price you qualify for even though the loan terms are otherwise similar.
Is refinancing from a 30-year to a 15-year worth doing if I'm several years into my mortgage?
Run the numbers rather than assuming — you'll restart amortization on a new loan, pay new closing costs, and take whatever rate is available then. If the new 15-year rate is meaningfully lower than your current rate, the math can still work in your favor even a few years in; if rates have risen since your original loan, the extra-payment approach above may capture more of the benefit without resetting your loan or paying new closing costs.
Run your own numbers
Every figure above uses one illustrative $300,000 home and this week's average rates — your actual quotes, loan amount, and down payment will shift the real numbers. Compare both terms, and the extra-payment middle ground, in our Mortgage Amortization Calculator, check overall affordability in our Home Affordability Calculator, and stress-test either payment against your full monthly budget in our Budget Calculator. If you're still saving toward a down payment, our Saving for a House Calculator can help you plan the timeline. Ask for Loan Estimates on both the 15- and the 30-year from at least three lenders on the same day — a bank, a credit union, and a mortgage broker — and compare the APR and the total-interest line, not just the monthly payment. Our Data Hub tracks current rate trends in the meantime.
Sources: Freddie Mac — Primary Mortgage Market Survey · Consumer Financial Protection Bureau — What Is a 15-Year Fixed-Rate Mortgage?
This is an estimate for educational purposes only. HowAffordable is not a lender or financial advisor — actual rates, terms, and qualification requirements vary by lender and borrower. See our methodology for full assumptions and sources.