🏦 Mortgage Calculator
Estimate the monthly payment for a fixed-rate home loan — and see exactly how much an extra monthly payment saves you in interest and time.
How to use the Mortgage Calculator
Enter the loan amount in dollars, the term in years and the annual interest rate, then pick a repayment style. The page returns a summary of monthly payment, total interest and total repaid, followed by an amortization schedule you can scroll through to check any single period.
How it works
A fully amortized loan uses a fixed monthly payment computed as payment = P × r × (1+r)n ÷ ((1+r)n − 1), where r is the monthly rate and n the number of periods. The interest-only loan applies a fixed amount to principal each month, so payments start high and decline. Both carry the same interest rate; the difference is purely how quickly principal is retired.
When to use it
Use it before signing a mortgage to compare lender quotes, to see the true cost of two repayment styles, to plan an extra-payment strategy, or to understand what a monthly payment actually buys.
Worked example
A $400,000 loan at 6.5% over 30 years:
| Item | Fully Amortized | Principal Only |
|---|---|---|
| First payment | $2,526.27 | $2,727.78 |
| Last payment | $2,526.27 | $1,406.32 |
| Total interest | $509,443.31 | $464,868.60 |
| Total repaid | $909,443.31 | $864,868.60 |
Assumptions and limitations
This calculator assumes a constant interest rate for the whole term. Adjustable-rate mortgages reset at scheduled intervals, which this tool cannot predict. Closing costs, property taxes, insurance, PMI and HOA dues are not included, so your real monthly cost will be higher. Verify all figures against your lender before relying on them.
Mortgage FAQ
How much does an extra monthly payment save?
On a $300,000 loan at 6.5% over 30 years, adding just $100/month cuts the payoff by about 3 years and saves roughly $77,000 in interest. Try your own numbers in the "extra monthly payment" field above.
How is the monthly payment calculated?
For a fixed-rate loan: M = P × r × (1+r)^n ÷ ((1+r)^n − 1), where P is the loan amount, r the monthly interest rate (annual ÷ 12) and n the number of months. Early payments are mostly interest; later ones are mostly principal.
What's included in a real mortgage payment?
This calculator shows principal and interest (P&I). Your actual payment usually also includes property taxes, homeowners insurance and possibly PMI and HOA fees — commonly called PITI.
Should I pay extra on my mortgage or invest instead?
It depends on your mortgage rate versus your expected investment return, and on having an emergency fund first. Paying extra is a guaranteed return equal to your loan rate; investing may earn more but carries risk.
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