30 Year Mortgage Calculator
See more than just your monthly payment: the total interest you’ll pay across 30 years, the exact year your payment flips from mostly-interest to mostly-principal, and a direct comparison against a 15-year loan on the same amount.
Reviewed for accuracy: August 2026 · Rate averages from Freddie Mac’s Primary Mortgage Market Survey
Your Loan Details
Taxes, Insurance & HOA
Monthly Payment
Where Your Payment Actually Goes, Year by Year
This is the part a monthly payment number hides completely. Watch the purple (interest) shrink and the green (principal) grow as the loan matures.
30-Year Balance & Equity Snapshot
Your remaining balance at key milestones, based on your numbers above.
| Year | Remaining Balance | Equity Built | Interest Paid To Date |
|---|
30-Year vs. 15-Year, Same Loan Amount
The 15-year loan usually carries a lower rate too, which makes the total interest gap even larger than the term difference alone would suggest.
30-Year Loan
- Monthly P&I: $0
- Total interest: $0
- Lower payment, more qualifying flexibility
15-Year Loan (Same Amount)
- Monthly P&I: $0
- Total interest: $0
- Interest saved vs. 30-year: $0
The Part of a 30-Year Mortgage Nobody Explains Well
Ask most people what happens in the first few years of a 30-year mortgage and they’ll describe paying down the loan. That’s technically true, but it dramatically understates what’s actually happening. Amortization calculates interest fresh each month against whatever balance remains, and in year one, that balance is essentially your entire loan. So the majority of your early payments go toward interest, not principal, and it takes years, sometimes over a decade depending on your rate, before the split flips and more of your payment starts building real equity than covering interest. This calculator’s principal/interest split chart above shows exactly where that crossover happens for your specific numbers.
This isn’t a flaw in your loan, it’s just how amortization math works on any fixed-rate loan, and it’s more pronounced on a 30-year term simply because the balance stays elevated for longer. It’s also exactly why paying extra toward principal early in a 30-year loan is so disproportionately effective: every extra dollar applied while the balance is still high avoids years of compounding interest that dollar would have otherwise generated.
Why the total interest number matters more than the monthly payment
A 30-year mortgage is sold on its monthly payment, and for good reason, it’s usually the lowest available payment for a given loan amount. But the total interest figure this calculator surfaces is the number that actually determines what the loan costs you, and it’s routinely larger than buyers expect walking in. On a typical loan, total interest over 30 years can exceed the original loan amount itself, which is a genuinely useful number to see plainly rather than discover gradually over three decades of statements.
Why so many 30-year borrowers still come out ahead
None of this means a 30-year mortgage is a mistake. The lower required payment creates real breathing room, improves approval odds, and, crucially, doesn’t obligate you to actually take 30 years to pay it off. A common and effective strategy is choosing a 30-year term for the payment flexibility, then voluntarily paying extra toward principal, whether every month or whenever cash allows, to capture something close to a 15-year payoff timeline without giving up the lower required minimum as a safety net during leaner months. Our Mortgage Calculator With Extra Payments is built specifically to show what that strategy does to your exact payoff date and interest total.
Frequently Asked Questions
It depends on your loan amount and rate, but the totals are larger than most borrowers expect. On a $400,000 loan at a 6.65% rate, a 30-year term results in roughly $524,000 in total interest, meaning you’d pay about $924,000 total for a $400,000 loan by the time it’s paid off.
Because amortization calculates interest on your remaining balance each month, and your balance is largest at the very start of the loan. Early payments are weighted heavily toward interest, and the split gradually shifts toward principal as your balance shrinks, which is why equity builds slowly in the first several years of a 30-year loan.
Historically and currently, 15-year fixed rates run roughly 0.6 to 0.8 percentage points below 30-year fixed rates on the same loan. As of August 2026, the national average 30-year rate is around 6.65 to 6.68 percent, while the 15-year average sits closer to 5.94 to 6.10 percent.
A 30-year mortgage offers a lower, more manageable monthly payment and more qualifying flexibility, at the cost of significantly more total interest. A 15-year mortgage saves a large amount of interest, often around 50 to 60 percent less than a comparable 30-year loan, but requires a meaningfully higher monthly payment. Many borrowers choose a 30-year loan for payment flexibility while making extra principal payments to shorten the effective payoff timeline.
Yes. Making extra principal payments, whether recurring monthly, an annual lump sum, or both, can shorten a 30-year mortgage by years and save substantial interest, without ever refinancing into a shorter-term loan or losing the lower required payment as a safety net.
Not inherently. It’s the most common mortgage structure in the U.S. for good reason: the lower required payment improves affordability and cash flow flexibility. The trade-off, meaningfully more total interest than a shorter term, is a known and manageable cost, especially for borrowers who plan to make extra payments or who value the lower monthly obligation.
It varies by rate, but on a typical current-rate 30-year loan, the crossover, the point where more of your payment goes to principal than interest, commonly lands somewhere between year 15 and year 20, depending on your specific rate. This calculator’s split chart shows the exact year for your own numbers.
Yes, generally. A new loan starts its own amortization schedule from month one, meaning even if you’re well past your original loan’s crossover point, a refinance restarts the interest-heavy early period on the new balance and term.
Standard fixed-rate 30-year mortgages all follow the same amortization math, interest calculated on the remaining balance each month. The specific numbers, including the crossover point, still shift based on your individual rate, since a higher rate keeps the interest-heavy period going longer.
PMI applies whenever your down payment is under 20% on a conventional loan, regardless of term length. This calculator includes an estimated PMI line automatically when your down payment falls below that threshold, on top of your principal, interest, taxes, and insurance.
Yes, typically through refinancing into a new 15-year loan once your finances and rates support the higher payment, though this involves closing costs and a new underwriting process. An alternative many borrowers use instead is simply making extra payments on the existing 30-year loan to approximate a 15-year payoff without refinancing.
Yes. Enter your annual property tax and homeowners insurance estimates, plus any monthly HOA dues, and the calculator combines them with principal, interest, and PMI (if applicable) into one complete monthly PITI payment.
Related Mortgage Calculators
- Mortgage Calculators Hub — browse every state-specific and loan-program calculator on DexoCalc, including FHA, VA, USDA, and PMI tools alongside this 30-year calculator.
- Main Mortgage Calculator — our full-featured PITI calculator if you want to adjust every input, including custom loan terms beyond 30 or 15 years.
- Mortgage Calculator With Extra Payments — the natural next step from this page: see exactly how much faster your 30-year loan pays off with recurring extra payments, a lump sum, or both.
- Mortgage Calculator With PMI — if your down payment is under 20%, model your exact PMI cost and cancellation timeline in detail.
- Mortgage Calculator By Income — not sure what loan amount you should even be running through this calculator? Work backward from your income first.
- First-Time Home Buyer Mortgage Calculator — if this is your first home purchase, compare FHA, VA, USDA, and Conventional 3% programs before locking in a 30-year rate.