Calculator
Polish mortgage overpayment calculator
Compare model payments and interest before and after a mortgage overpayment. Data is processed only in your browser, and the page explains the formula and limitations of the result.
Calculator
Enter data
Principal, annual rate, remaining payments and one-off overpayment. Fields marked with an asterisk are required.
How to use the calculator
- Enter the required data: principal, annual rate, remaining payments and one-off overpayment.
- Check the values and select “Calculate”.
- Review the primary result and the detailed calculation components.
Calculation details
Formula and calculation method
Payments use the annuity model. The overpayment reduces principal while payment count and interest rate remain unchanged.
Worked example
For PLN 300,000 principal, 7% and 240 payments, a PLN 30,000 overpayment reduces model principal to PLN 270,000 and lowers the payment.
Limitations
- A bank may charge a fee, recalculate the schedule differently or shorten the term instead of reducing the payment.
Sources
Engine version: 1.0 · Last reviewed: 3 August 2026
Frequently asked questions
Is the entered data sent to a server?
No. The calculation runs locally in your browser and the values are not saved by default.
Is the result definitive?
Not always. A bank may charge a fee, recalculate the schedule differently or shorten the term instead of reducing the payment.