Mortgage Calculator
Enter your numbers below — your monthly payment updates instantly, with the full breakdown, total interest, payoff date, and a side-by-side 15 vs 30-year comparison. No sign-up. The exact formula is shown so you can verify every figure.
Taxes, insurance & fees (optional)
Quick answer
On a $400,000 home with $80,000 down at 6.5% over 30 years, the monthly payment is $2,572.62 — and that includes property tax, insurance and PMI, not just principal and interest. Over the full term you would pay $408,142 in interest. Change the inputs above and this answer updates with your own numbers.
How your balance falls over time
Blue = remaining balance. Early payments are mostly interest; principal accelerates later.
15 vs 20 vs 30-year — what each really costs you
Same loan amount and rate. The shorter term costs more per month but saves you a fortune in interest.
| Term | Monthly (P&I) | Total interest | Total paid |
|---|
What is actually in a mortgage payment
The number a lender quotes you and the number that leaves your account each month are rarely the same, and the gap is where budgets break. A full payment usually has four parts, often abbreviated PITI:
- Principal — the part that reduces what you owe. Early on this is the smallest slice.
- Interest — the lender's charge on the outstanding balance. Early on this is the biggest slice.
- Taxes — property tax, usually collected monthly into an escrow account and paid on your behalf.
- Insurance — homeowner's insurance, and PMI if your deposit is under 20%.
This calculator includes all four, which is why its figure is higher than a bare principal-and-interest quote. On the default $400,000 example, principal and interest alone are about $2,023 a month; tax, insurance and PMI add roughly $550 more. Budgeting on the smaller number is one of the most common and most expensive mistakes a first-time buyer makes.
15 vs 20 vs 30 years — what each really costs
The term is the single largest lever you control, and its effect is deeply asymmetric. Same $320,000 loan at 6.5%, same taxes and insurance:
| Term | Monthly payment | Total interest | Total paid |
|---|---|---|---|
| 15 years | $3,337.54 | $181,758 | $501,758 |
| 20 years | $2,935.83 | $252,600 | $572,600 |
| 30 years | $2,572.62 | $408,142 | $728,142 |
Read the two ends against each other. The 30-year payment is $765 a month lower — real, immediate breathing room. It also costs $226,384 more in interest, which is more than half the price of the house again.
Neither is simply correct. A 15-year term is cheaper in total but commits you to a payment you cannot lower if your income drops. A 30-year term is more expensive but flexible: you can always pay a 30-year mortgage like a 15-year one, and stop when life demands it. What you cannot do is go the other way.
Why a rate change moves so much money
On a loan this size, each percentage point of interest is worth roughly $200 a month and tens of thousands over the term. That is why shopping the rate matters more than almost any other decision in the process, and why a fraction of a point is worth arguing about.
It is also why the term and the rate should be considered together rather than separately. A shorter term usually carries a slightly lower rate, so the total-cost gap between 15 and 30 years is often wider in practice than the table above suggests.
What your deposit changes, beyond the loan size
A larger deposit obviously shrinks the loan. Less obviously, crossing 20% normally removes PMI — mortgage insurance that protects the lender, not you, and adds a cost that buys you nothing. On the default example PMI is charged at 0.5% of the loan a year, roughly $133 a month, and it disappears entirely at a 20% deposit.
So the last few thousand dollars of deposit before that threshold often do more work than any amount after it. Set the deposit to 20% in the calculator above and watch two things move at once: the loan shrinks, and a line item vanishes.
The mortgage payment formula
- M — monthly principal and interest
- P — the loan amount, meaning price minus deposit
- r — monthly interest rate, the annual rate divided by 12
- n — total number of monthly payments (years × 12)
Taxes, insurance and PMI are not in that formula — they are added on top, which is precisely why a payment quoted from it always looks lower than the real one.
See the formula with your own numbers
These update live from the calculator inputs above.
Example: $400,000 home, 20% down vs 20% down
The default scenario is a $400,000 home with $80,000 down — exactly 20% — a $320,000 loan at 6.5% over 30 years, $4,800 annual property tax and $1,800 insurance.
- Monthly payment: $2,572.62, of which about $2,023 is principal and interest and about $550 is escrow.
- Total interest over 30 years: $408,142 — more than the loan itself.
- Total paid: $728,142 on a $400,000 house.
That last line is the one worth sitting with. At 6.5% over a full 30-year term, the interest exceeds the amount borrowed. It is not a sign of a bad deal — it is simply what borrowing a large sum for three decades costs, and it is the reason the term and rate deserve more attention than the wallpaper.
Frequently asked questions
How much house can I afford?
Lenders commonly look at your total housing payment against gross income, and many use a guideline of roughly 28% of gross income for housing and 36% for all debt combined. Those are underwriting limits, not advice — plenty of people are approved for payments they later find uncomfortable. A more useful test is to run the full payment here, including tax, insurance and PMI, and ask whether you would still be comfortable with it if your income fell.
Does this calculator include property tax and insurance?
Yes. It shows the complete monthly cost including property tax, homeowner's insurance, PMI and any HOA fee, because that is what actually leaves your account. Most quoted mortgage figures show principal and interest only, which on the default example understates the payment by about $550 a month.
What is PMI and when does it stop?
Private mortgage insurance protects the lender if you default. It is normally required when your deposit is under 20% of the price, and it is charged as a percentage of the loan each year. It typically ends once you reach roughly 20-22% equity, either by paying down the balance or through appreciation, though you may have to request cancellation rather than wait for it.
Is a 15-year mortgage better than a 30-year?
Cheaper, not automatically better. On the default $320,000 loan the 15-year term saves $226,384 in interest but costs $765 more every month. The 30-year gives you the option to pay like a 15-year without the obligation to. If your income is stable and the higher payment is comfortable, 15 years wins on cost; if there is any doubt, the flexibility has real value.
How much difference does one percentage point make?
On a $320,000 30-year loan, roughly $200 a month and tens of thousands over the term. That is why shopping several lenders is worth more than almost anything else you can do in the process, and why a quarter of a point is worth negotiating.
Should I make extra payments?
Extra principal shortens the loan and cuts total interest, because every extra dollar removes all the future interest that dollar would have accrued. It is most powerful early, when the balance is largest. If you would rather lower the required payment than finish early, look at a mortgage recast instead — same lump sum, opposite effect.
Method & sources
- Calculation: Standard fixed-rate amortization (formula shown above). Figures are estimates and exclude closing costs and rate changes.
- PMI & DTI guidance based on Consumer Financial Protection Bureau (CFPB) homebuyer guidance.
- Reviewed: · We update rates guidance and assumptions quarterly.
This is an educational estimate, not financial advice. Confirm exact figures with your lender.
Run your own numbers
Enter your price, deposit, rate and term and see the full monthly payment — principal, interest, tax, insurance and PMI — plus what each term costs you in total.
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