Mortgage Calculator
The full payment — principal, interest, taxes, insurance, PMI, HOA — plus real PMI cancellation math and an honest refinance check.
Also known as: Home loan calculator, PMI calculator, Refinance break-even calculator, Amortization schedule calculator
How it works
- 1Enter your home price, down payment (as a dollar amount or percentage — they stay in sync), interest rate, and loan term.
- 2Add property tax, home insurance, HOA fees, and a PMI rate if your down payment is under 20% — your full monthly payment updates instantly.
- 3Optionally add an extra monthly payment, a one-time extra payment, or switch to biweekly payments to see the real time and interest saved.
- 4Browse the full amortization schedule, download it as a CSV, or open the refinance panel to check whether refinancing your current loan actually makes sense.
Why use Mortgage Calculator
No lender leads, ever
No email capture, no "connect with a loan officer" form — mortgage calculators are a standard industry lead-generation tool, and this one deliberately isn't one.
The complete monthly payment
Principal, interest, property tax, home insurance, PMI, and HOA — combined into one real number with a full breakdown, not just principal and interest.
Real PMI cancellation math
Simulates your actual amortization schedule to find the exact month PMI is projected to auto-cancel at 78% of your original home value, plus the total PMI cost until then.
Honest refinance comparison
Shows the full-term total-interest comparison alongside the monthly savings, so a lower payment from resetting your loan term doesn't hide a worse overall deal.
Extra & biweekly payment impact
See the exact months and dollars saved from an extra monthly payment, a one-time lump sum, or switching to biweekly payments — visualized against the standard schedule.
Nothing ever leaves your browser
Every calculation runs as plain JavaScript in the page itself — your financial details are never transmitted anywhere.
Who uses Mortgage Calculator
Working out what you can actually afford monthly
See the full payment — including taxes, insurance, and PMI — before falling in love with a listing based on principal and interest alone.
Deciding whether to put down 20% to skip PMI
Compare the monthly payment and total cost with and without PMI to see whether waiting to save a bigger down payment is worth it for your situation.
Planning extra payments toward your mortgage
See exactly how much time and interest a specific extra monthly amount or a one-time bonus payment would actually save.
Deciding whether to refinance
Check the real break-even point on closing costs and the full-term interest comparison before refinancing into a new rate or term.
Understanding when PMI will actually drop off
Get a real projected month and date instead of a vague "once you reach 20% equity" statement with no number behind it.
About Mortgage Calculator
Most free mortgage calculators online exist to capture a lead, not to answer your question. Search for one and the pattern repeats: a simple payment estimate, followed by a form asking for your email or phone number to "see your rate" or "get connected with a lender." That's not an accident — mortgage calculators are a well-documented, standard lead-generation tool across the industry, built specifically to feed loan officers a list of people who just showed interest in buying a home. This calculator has no such form, because it isn't trying to sell you anything — it just answers the question.
Beyond the lead-generation issue, most free calculators are also incomplete. A principal-and-interest number alone isn't your actual monthly payment — property tax, home insurance, PMI, and HOA fees are real, recurring costs that change what a home actually costs you every month, and this calculator includes all of them in one number, with a breakdown showing exactly what each piece is.
The PMI math specifically gets skipped or oversimplified almost everywhere. Under the federal Homeowners Protection Act, PMI is required to automatically cancel once your amortized loan balance reaches 78% of your home's original value — not your loan amount, and not your home's current market value. This calculator simulates your actual amortization schedule month by month to find that exact point, so you see a real projected date and total PMI cost instead of a vague "PMI applies below 20% down" disclaimer with no number attached.
The refinance section is built around a comparison most calculators skip entirely: refinancing into a lower monthly payment by resetting your loan back to a fresh 30-year term can cost you more in total interest over time than staying on your current loan, even at a lower rate — because you're starting the interest-front-loaded amortization clock over again. This calculator shows both numbers side by side — the monthly savings and the full-term interest comparison — so a smaller monthly payment doesn't quietly hide a worse deal.
Mortgage Calculator vs. other options
How Open Tools Library compares to desktop software and other online tools.
| Feature | Open Tools Library | Desktop software | Other online tools |
|---|---|---|---|
| Lead capture / lender contact forms | Never | N/A | Extremely common — the industry standard model |
| PMI auto-cancellation date | Calculated exactly, from real amortization | Varies | Often a vague disclaimer, no real date |
| Refinance shows full-term interest, not just monthly savings | Yes, always shown | Rarely | Rarely — usually just the payment drop |
| Price | Free, unlimited | Often bundled in paid software | Free, but monetized via your submitted contact info |
| Data privacy | Never leaves your device | Stays local | Often collected for lender referrals |
Pro tips
- PMI is calculated against 78% of your original home price, not your loan amount or current market value — a detail that changes the payoff-month estimate meaningfully.
- A lower monthly payment from refinancing isn't automatically a better deal — check the full-term interest comparison in the refinance panel before deciding, especially if you're resetting back to a 30-year term.
- Biweekly payments are modeled the standard way every mortgage calculator uses: as one extra monthly-equivalent payment spread across the year, not a real biweekly billing simulation, since actual biweekly servicer timing varies by lender.
- Property tax and home insurance vary a lot by location — use your actual estimated annual figures rather than a generic default for an accurate total payment.
- A one-time extra payment applied early in the loan saves far more total interest than the same amount applied later, because it reduces the balance interest accrues on for the entire remaining term.
- Download the full CSV schedule if you want to dig into a specific month or year, or drop it into your own budgeting spreadsheet.
Technical specs
- Included in monthly payment
- Principal, interest, property tax, home insurance, PMI, HOA
- PMI cancellation rule modeled
- 78% of original home value (Homeowners Protection Act)
- Extra payment options
- Recurring monthly, one-time lump sum, biweekly
- Refinance comparison
- Monthly savings + full-term total interest difference
- Lead capture / lender contact forms
- None
- Processing location
- 100% local, in your browser
Privacy & security
Most free mortgage calculators exist to collect your contact details for a lender — which is exactly why this one doesn't ask for any.
Every calculation runs locally in your browser — your home price, income, and loan details are never transmitted anywhere.
No email, phone number, or account is ever requested, and nothing is shared with lenders or loan officers.
Nothing about your inputs or results is stored anywhere once you close the tab.
Equally private whether you're browsing homes casually or actively comparing refinance offers.
Frequently asked questions
Is my financial information uploaded anywhere?
No. Every calculation runs locally in your browser as plain JavaScript — nothing about your loan, income, or home details is ever sent to a server.
Will I be contacted by a lender or loan officer after using this?
No — there's no contact form, no email capture, and no lead-sharing of any kind. This is a deliberate difference from most free mortgage calculators, which exist specifically to generate leads for lenders.
How is PMI calculated?
PMI is estimated as a percentage of your loan amount (which you can adjust), applied monthly while required, and projected to auto-cancel once your amortized balance reaches 78% of your original home price — the federal Homeowners Protection Act threshold.
Can I see the full amortization schedule, not just a summary?
Yes — toggle to the full monthly view or keep the condensed yearly view, and download the complete schedule as a CSV either way.
Does the refinance calculator account for closing costs?
Yes — enter your estimated closing costs and it calculates the exact number of months needed to break even on them from your monthly savings, alongside the full-term total interest comparison.
Troubleshooting
My PMI cancellation month seems different from my lender's estimate
This tool models the federal 78%-of-original-home-value auto-cancellation rule exactly. Some lenders let you request cancellation earlier, at 80% equity, or use current appraised value instead of original purchase price — check your specific loan's PMI terms if the numbers need to match precisely.
Why does refinancing show a lower monthly payment but MORE total interest?
This happens when a new loan resets the term back to something like 30 years — even at a lower rate, restarting the interest-front-loaded amortization clock can cost more in total interest than finishing out your current, shorter remaining term. The refinance panel shows both numbers specifically so this isn't hidden.
Does the biweekly option simulate real biweekly billing?
It uses the same simplified, standard model every mortgage calculator uses: one extra monthly-equivalent payment applied evenly across the year, equal to what 26 half-payments (13 full payments) works out to. Real biweekly servicer administration and interest-accrual timing varies by lender and isn't standardized enough to model exactly.
My down payment percentage and dollar amount don't match after I edited one
They're kept in sync automatically — editing either field recalculates the other against your current home price. If you change the home price after setting a down payment, the percentage is kept fixed and the dollar amount updates to match it.
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