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🏠 Mortgage Calculator
The mortgage payment your loan officer quotes is one number. The number that actually matters is what you'll pay in total over thirty years, and the curve showing why almost none of your early payments touch the principal. This calculator gives you both. Put in loan amount, rate, and term. Get the monthly payment plus the full amortization table, so you can see how much of payment #1 evaporates as interest (a lot) versus how much chips at the balance (almost none).
Examples
$320,000 loan @ 7% × 30yMonthly: $2,129 · Total interest: $446,428$320,000 loan @ 6.5% × 15yMonthly: $2,788 · Total interest: $181,81515-year payment is higher but saves $260k+ in interest.
$200,000 loan @ 6.8% × 30yMonthly: $1,304 · Total interest: $269,400Frequently asked questions
What costs are NOT included in the payment?
Property tax, homeowners insurance, HOA fees, and PMI (private mortgage insurance, usually required if down payment is under 20%). Add these on top of the principal + interest payment shown.
What is PMI and how do I avoid it?
PMI protects the lender if you default. Typically 0.5–1% of the loan annually. Avoid it by putting 20% or more down, or by choosing a loan program that does not require it (some VA / physician loans).
How much does the interest rate matter?
Massively. On a $400k 30-year loan, every 1% rate change shifts the monthly payment by roughly $250 and total interest by ~$90k.
Should I get a 15-year or 30-year?
The honest answer: take the 30-year and pay extra principal voluntarily. You get the lower required payment as a safety net, but if you discipline yourself to add $400-500/month to principal, you finish in roughly 18-20 years and save most of what a 15-year would. The 15-year only wins if you genuinely cannot help yourself spending the difference.
Can extra principal payments help?
A lot. An extra $200/month on a $400k 30-year at 7% can shave ~6 years off and save ~$130k in interest. Make sure to specify "apply to principal" so the lender does not just count it as next month's payment.
About this tool
Mortgage Calculator runs entirely in your browser using standard Web APIs. No data is sent to any server. The source for this tool is in our public GitHub repository.
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Why this tool
vs typical free web-tool sites
| 1vw | Typical free site | |
|---|---|---|
| Price | Free | Free |
| Signup required | No | Often (for premium features) |
| Ads inside the tool | No | Yes (banner + video) |
| Data sent to server | No (browser-only) | Yes (inputs analyzed for ads) |
| Total tools | 96 | Often <20 or scattered across sites |
| Bookmarkable URL per tool | Yes | Mixed |
| Loads in under 1s | Yes (static) | Often slow (ad tracking) |
| Multilingual | EN / ES / PT / FR / DE | Usually EN only |
| Open source | Yes | No |