What will your mortgage really cost?
We built this because every other mortgage calculator we tried either ignored PMI, hid the amortization schedule behind a signup form, or only knew one country's rules. Ours doesn't. It uses the same PMT formula your bank uses — accurate to the cent — and handles US, UK, and French mortgages with all the country-specific taxes, insurance, and quirks that actually move your monthly payment.
Mortgage calculator
For informational purposes only. Not financial advice. Always confirm with your bank's official offer before signing.
Where your monthly payment goes
Each component as a share of your monthly cost.
Equity vs interest paid over time
Cumulative principal repaid against interest paid, year by year.
Amortization schedule
How each payment splits between principal and interest over time.
| Period | Payment | Principal | Interest | Extras | Balance |
|---|
About this mortgage calculator
This is the calculator we wished existed when we were shopping for a mortgage ourselves. It computes the exact monthly payment, total interest, and full amortization schedule for a fixed-rate loan using the standard PMT formula every bank uses. Numbers are accurate to the cent — the rounding error gets absorbed into the final payment so the schedule closes at zero, the same way a real loan does.
Three countries, with the actual taxes and fees that matter in each:
- United States. Property tax, homeowners insurance, HOA, and PMI — auto-applied when your down payment is below 20%, and auto-removed when LTV hits 78% per the Homeowners Protection Act of 1998. Most calculators skip the auto-removal step. We didn't.
- United Kingdom. Stamp duty land tax (current HMRC residential brackets for England and Northern Ireland) plus buildings insurance.
- France. Frais de notaire (ancien or neuf/VEFA), assurance emprunteur, taxe foncière. The bits that turn a French mortgage quote into a real total cost.
You can also model an interest-only deferral period of up to 36 months (common on French VEFA new-builds and UK interest-only periods) and a one-time extra principal payment, with the option to either shorten the term or lower the monthly payment.
For the deeper "why" behind the math, see how mortgage payments are calculated, how to read an amortization schedule, or PMI explained.
Frequently asked questions
How is my monthly mortgage payment calculated?
The standard formula is M = P × [r(1+r)^n] / [(1+r)^n − 1], where P is the loan amount, r is the monthly interest rate, and n is the number of months. We compute this exactly and build the full month-by-month schedule.
Does this work for UK or French mortgages?
Yes. The country selector at the top adjusts the form fields. The core math is universal; only the additional fees and taxes differ.
What is interest deferral?
A period at the start of the loan during which you pay only interest, not capital. Common in France for VEFA (new-build) and in the UK as interest-only periods. Our calculator supports up to 36 months.
Can I model an extra principal payment?
Yes. In the deferral & extra payment section, set the month and amount, and choose whether to keep the term (and lower the monthly) or keep the monthly (and shorten the term).
Is this tool accurate enough for a real loan decision?
The math matches Excel's PMT formula to the cent. Country-specific fees use published reference rates but always confirm with your bank's official offer before signing.