Loan & Mortgage Calculator
Enter your loan amount, interest rate, and term to instantly calculate your monthly payment, total interest, and a full amortization schedule. Add an optional extra payment to see exactly how much time and money you save. All calculations run entirely in your browser — no data is sent to any server.
How the Monthly Payment is Calculated
The tool uses the standard PMT formula (the same one Excel uses):
Payment = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)
- P — Loan principal (the amount borrowed)
- r — Monthly interest rate = annual rate ÷ 12 ÷ 100
- n — Number of monthly payments (years × 12)
For a €200,000 mortgage at 4 % over 30 years, this gives a monthly payment of €954.83 and total interest of €143,739.
Understanding the Amortization Schedule
Every fixed-rate loan follows the same pattern: early payments are mostly interest, later payments are mostly principal.
| Year | Principal paid | Interest paid | Remaining balance |
|---|---|---|---|
| 1 | low | high | near original |
| 10 | growing | shrinking | ~50 % gone |
| 30 | high | near zero | €0 |
The bar chart visualises this shift — the blue (principal) bars grow each year as the red (interest) bars shrink.
The Power of Extra Payments
Even a small monthly overpayment has a compounding effect:
- €100/month extra on a €200,000 / 4 % / 30-year loan saves roughly 3–4 years and over €20,000 in interest.
- €300/month extra cuts the term by nearly 10 years.
The extra payment calculator shows the exact months saved and interest saved for any overpayment amount.
Compare Two Scenarios
Use the Compare mode to evaluate decisions side-by-side:
- Should I choose a 15-year or 30-year term?
- How much does 0.5 % less interest save over 25 years?
- Fixed rate vs. variable rate — what’s the break-even overpayment?
Download Your Plan
Click Download CSV to export the annual amortization table. Import it into Excel or Google Sheets to build a full monthly breakdown, create charts, or combine it with your household budget.
Disclaimer
This tool provides estimates based on the PMT formula for standard annuity loans. Results do not account for fees, insurance, irregular repayments, variable interest rates, or country-specific tax rules. Always verify figures with your lender or a qualified financial advisor before making borrowing decisions.