Mortgage overpayment calculator: how much interest you save
Enter the principal left, your interest rate and the remaining term, then a one-off or monthly overpayment. You will see the interest you save, when the loan ends and whether a shorter term or a lower instalment pays off more.
Your result
Enter your loan’s interest rate. The amount, term and overpayment are already filled in. The result will appear here straight away.
You save on interest
- Current instalment
- New instalment
- Loan ends with overpayment
- Loan ends without overpayment
- Interest without overpayment
- Interest with overpayment
- Overpayment fee
Free of charge. We compare your loan with offers from 14 banks.
An illustration, at your current interest rate until the end, or with the change you enter. Details
The bank calculates the overpayment from its own schedule and payment date, so the amounts may differ slightly.
Shorter term or lower instalment?
The same overpayment, two ways to apply it.
| After overpaying | Instalment | Loan ends | Saving |
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Overpay or put it in a deposit?
Every złoty you overpay stops costing you interest. It is a gain with no risk and no tax.
An overpayment does not come back: keep a cushion of 3–6 months of expenses first. Details
With a fixed rate the gain is certain until the fixed period ends, then it depends on the new rate.
How much of the loan is left
Principal at the end of each year, without and with the overpayment.
Hover over a bar or tap it to see the amounts for that year.
Shorter term or lower instalment
- Shorter term. The instalment stays the same and the loan ends earlier. This almost always saves the most interest, because the debt disappears faster.
- Lower instalment. The term stays the same and the instalment falls. You save less interest, but you get more room in your budget and a higher borrowing capacity later.
Overpaying a mortgage in Poland
- You can overpay at any time. Polish law lets you repay a mortgage early, in full or in part (Article 39 of the Act on mortgage credit).
- Fee. With a variable rate the bank may charge compensation only in the first 3 years of the agreement, at most 3% of the amount overpaid and no more than one year of interest (Article 40). With a fixed rate, the agreement sets the rules for the fixed period. Many banks charge nothing.
- How to do it. Order the early repayment in your banking app or at a branch, choose a shorter term or a lower instalment, then download the new schedule.
How we calculate
We simulate the loan month by month: equal or decreasing instalments at your interest rate, the one-off overpayment deducted from the principal now or after the months you enter, and the monthly overpayment added to each instalment. With a shorter term the instalment stays as in the agreement; with a lower instalment it is recalculated after each overpayment. The bank fee is deducted from the saving.
Frequently asked questions
What pays off more: a shorter term or a lower instalment?
With the same overpayment, a shorter term almost always saves more interest, because the debt disappears faster. A lower instalment gives you more room in your budget and a higher borrowing capacity in future. The calculator shows both side by side.
Can a Polish bank charge a fee for overpaying a mortgage?
For agreements signed from 22 July 2017 with a variable rate, only in the first 36 months of the agreement, at most 3% of the amount overpaid and no more than one year of interest on it (Article 40 of the Polish Act on mortgage credit). With a fixed rate the bank may charge it during the fixed period. In both cases the fee must be in the agreement and cannot exceed the bank’s costs. Many banks charge nothing.
Should I overpay my mortgage or invest?
An overpayment earns the same as your loan’s interest rate, with no risk and no tax. With a variable rate this gain moves with WIBOR. An investment may earn more or less. Before you overpay, keep a cushion for a few months of expenses, because the bank will not give the money back.
Does an overpayment lower the instalment automatically?
It depends on the bank and the agreement. Usually when you order the overpayment you choose a shorter term or a lower instalment. If you do not choose, the bank applies the setting from your agreement.
Is it better to overpay or to refinance?
One does not rule out the other. If another bank offers a lower margin or a better fixed rate, refinancing lowers the cost of the whole remaining debt, not just the part you overpay. See our refinancing calculator.
This guide describes general rules and typical bank practice as of October 2026. Details
It is not legal or tax advice and not a bank offer. Each bank sets its own criteria, and the lending decision is always made by the bank.