Calculator
Mortgage overpayment calculator: shorten the term or lower the instalment?
Enter the balance from your bank schedule and the overpayment – one-off or monthly. The calculator shows interest saved in both modes side by side, how much shorter the loan gets or what the new instalment is, and deducts the bank fee if the contract is under 3 years old.
Less interest
105 953zł
- Loan shorter by
- 4 yrs 9 mo.
- Instalment today
- 2 696,96 zł
- Interest without overpayment
- 311 995 zł
- Interest with overpayment
- 206 042 zł
Same transfer, two modes
Shorter term
−105 953 zł
4 yrs 9 mo.
Lower instalment
−38 828 zł
2 359 zł
- Balance with overpayment
- Balance without overpayment
Indicative result – not a loan offer or investment advice. Statutory and market parameters checked on 2026-10-10.
An indicative tool: the result is an order of magnitude on your assumptions, not a valuation or tax, legal or investment advice. Data entered into the form is never sent or stored anywhere.
How it is computed
- 1Two schedulesA schedule without and with the overpayment, month by month. In “shorter term” mode the instalment stays and the balance falls faster. In “lower instalment” mode the bank recalculates the instalment on the new balance over the remaining term.
- 2Overpayment feeWith a variable rate the bank may charge compensation only during the first 36 months: at most 3 % of the overpaid amount and no more than one year of interest on it (Art. 40 of the Mortgage Credit Act). Many banks charge nothing.
Frequently asked questions
Which pays off more: shorter term or lower instalment?
In interest, always the shorter term, because principal falls faster in every following month. A lower instalment makes sense when the budget is tight or when you plan to overpay the difference monthly – then the effect approaches shortening the term.
Can the bank charge an overpayment fee?
For a variable-rate mortgage – only in the first 3 years and at most 3 % of the overpayment. For a periodically fixed rate the bank may claim its actual costs throughout the fixed period. Check your bank’s fee schedule.
Overpay a lump sum now or monthly?
The earlier a złoty hits the principal, the more interest it saves – so a lump sum now beats the same total spread over years. But monthly overpayments do not eat your emergency fund. The calculator accepts both at once.
Let’s talk about your situation
Write a few sentences about the company and the problem. I reply within two working days and the first conversation is free.
Write to me