Mortgage calculator
Calculate your monthly mortgage payment: instalment, total interest and total cost. Free mortgage calculator 2026.
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APR (RRSO) calculator
Enter the amount, instalment, number of months, commission and insurance — the calculator returns APR, total cost and total repayment.
How we calculate APR
APR is found using Newton-Raphson for the monthly IRR: APR = (1 + IRR)^12 − 1. IRR is the internal rate of return of the loan cash flows.
Example: PLN 10,000, 12 months, instalment PLN 879
For a PLN 10,000 loan, PLN 879 instalment over 12 months: APR ≈ 10%. A PLN 500 commission raises APR to about 17%.
Frequently asked questions
What is APR (RRSO)?
APR (Annual Percentage Rate) is the total cost of a loan expressed as an annual %, including interest, fees and insurance.
What is the difference between interest rate and APR?
The interest rate covers only the capital cost; APR includes all fees — it is a fuller cost measure.
Why can APR be higher than the interest rate?
Commission, insurance and other fees increase the real cost, pushing APR above the nominal rate.
How do I compare loans using APR?
The lower the APR, the cheaper the loan. Compare APR at the same amount and period.
Does APR account for rate changes?
APR for a variable-rate loan is calculated at the time of signing — it does not reflect future rate changes.
What is IRR in the context of APR?
APR is derived from the IRR (internal rate of return) of loan cash flows, scaled to annual.
Can APR = 0%?
Formally yes (e.g. 0% commission and interest), but this is marketing — the cost may be hidden elsewhere.
How does EU law regulate APR?
Directive 2008/48/EC requires APR to be disclosed for consumer credit, enabling comparison of offers.
What is included in APR?
Interest, origination fee, mandatory insurance. Not included: late-payment fees, penalties.
Is the calculator result accurate?
The calculator uses Newton-Raphson for monthly IRR. The result is indicative — details in the contract.
Indicative result
The result is indicative. The calculator uses the Newton-Raphson method. Full details are in the credit agreement.
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