Mortgage Calculator
Determine your monthly mortgage payment and generate an estimated amortization schedule. See how much interest you will pay and how prepayments shorten your loan.
A worked example
Running this tool on current national benchmarks (Federal Reserve / Freddie Mac via FRED (St. Louis Fed)) — swap in your own numbers to see how the result moves.
- Home price
- $360,000
- Down payment
- $72,000
- Interest rate (APR)
- 6.50%
- Loan term
- 30 years
- Extra monthly payment
- $0
- Lump-sum prepayment
- None
- Schedule detail
- Yearly
$288,000 financed at 6.50% · 30-year term
- Principal & interest$1,820.36
- Total interest paid$367,328
- Total of payments$655,328
How the estimated monthly payment changes with home price
Holding the other inputs at the example above, here is how the result moves as home price changes.
| Home price | Estimated monthly payment | Principal & interest |
|---|---|---|
| $250,000 | $1,125.08 | $1,125.08 |
| $350,000 | $1,757.15 | $1,757.15 |
| $450,000 | $2,389.22 | $2,389.22 |
| $600,000 | $3,337.32 | $3,337.32 |
| $750,000 | $4,285.42 | $4,285.42 |
The math behind it
Your loan is the home price minus your down payment. The calculator amortizes that amount at your rate over your term using the standard mortgage formula, producing a fixed monthly principal-and-interest payment and a full schedule of how each payment splits between the two. Any extra monthly amount or one-time and yearly lump-sum prepayments are applied straight to principal, which shortens the loan and cuts total interest. It also reports your loan-to-value and flags whether PMI is likely.
What each input means
- Down payment
- Cash paid up front. The rest is financed.
- Extra monthly payment
- Additional principal paid each month.
- Starting at payment #
- Which monthly payment the prepayment(s) begin with.
Assumptions & limits
- The monthly payment shown is principal and interest only. Property taxes, homeowners insurance, PMI, and HOA dues are not added — use the taxes-and-insurance or PMI calculator for a full PITI figure.
- A single fixed interest rate is assumed for the entire term.
- Extra payments and lump sums are applied entirely to principal, starting at the payment number you choose.
- Loan-to-value is reported and PMI is flagged above 80%, but PMI cost is not built into the payment here.
- Interest is compounded monthly on the outstanding balance.
Source: Freddie Mac PMMS via FRED. Annual averages; latest weekly reading shown.
Common questions
Does this payment include taxes and insurance?
No. This calculator shows principal and interest only. Property taxes, homeowners insurance, PMI, and any HOA dues are billed on top — often adding hundreds of dollars a month. For the full monthly housing cost, use the mortgage calculator with taxes and insurance.
How much do extra payments actually save?
Because extra payments go straight to principal, they remove all the future interest that principal would have accrued. Even a modest amount added every month can trim years off a 30-year loan. Enter an extra amount or a lump sum and the results show the interest saved and how much earlier the loan is paid off.
What is loan-to-value and why does it matter?
Loan-to-value is your loan divided by the home price. Above 80% — meaning less than 20% down — lenders generally require private mortgage insurance. This calculator flags that threshold so you can see whether your down payment clears it.
Why is total interest often close to the amount borrowed?
Over a 30-year term at typical rates, the interest paid can approach or exceed the original principal, because you are paying interest on a large balance for many years. Shortening the term or prepaying principal is what brings that total down.