Calculator
Polish late-payment interest calculator
Calculate simple Polish late-payment interest using the annual rate entered. Data is processed only in your browser, and the page explains the formula and limitations of the result.
Calculator
Enter data
The amount, late-payment rate and days in one rate period. Fields marked with an asterisk are required.
How to use the calculator
- Enter the required data: the amount, late-payment rate and days in one rate period.
- Check the values and select “Calculate”.
- Review the primary result and the detailed calculation components.
Calculation details
Formula and calculation method
Interest = obligation amount × annual late-payment rate × number of days ÷ 365.
Worked example
For PLN 2,000, a 10% rate and 45 days, simple interest is about PLN 24.66 before applicable rounding.
Limitations
- Commercial transactions, contractual terms and rate changes may use rules different from ordinary statutory late interest.
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. Commercial transactions, contractual terms and rate changes may use rules different from ordinary statutory late interest.