About Liczymy Finanse

Liczymy Finanse (Polish for “we do the money maths”) is a set of free financial calculators for people who want to work out important decisions themselves: whether to overpay a mortgage or invest instead, whether to buy a home or rent, how much treasury bonds and bank deposits will earn after tax, what money from years ago is worth today, whether to save through an IKE, an IKZE or PPK, how much savings will grow and when early retirement is possible. The calculators work in Polish złoty, and their defaults reflect conditions in Poland.

Updated: October 22, 2026

Our calculators

Mortgage Overpayment Calculator — See how much you can save by overpaying your mortgage. Compare shortening the loan period vs reducing monthly installments.
Overpay the Mortgage or Invest? — Find out what leaves you better off: overpaying your mortgage or investing the same money. With Polish capital gains tax and the break-even return.
Buy or Rent a Home? — Buy a flat with a mortgage, or rent and invest the difference? See which leaves you better off and after how many years buying pays off.
Polish treasury bonds calculator — Compare EDO, COI, TOS, ROS and ROD bonds from the current offer: profit after Belka tax, with inflation and early redemption.
Polish bank deposit calculator — What will a bank deposit earn after Belka tax? Interest at each capitalisation, renewals and a check against the latest GUS inflation.
Compound Interest Calculator — See how your savings grow with regular contributions — after inflation and Polish capital gains tax.
Polish inflation calculator — What is money from years ago worth today? Work out inflation in Poland between any two months since 1991, using up-to-date GUS data.
IKE, IKZE or PPK? — IKE, IKZE or an ordinary account: which leaves you more for retirement? With the IKZE tax refund, the limits and a PPK comparison.
FIRE Calculator — Find out when you can retire early. Calculate your FIRE number and see your path to financial independence.

Our guides

Mortgages and housing

When doesn't overpaying your mortgage pay off? Overpaying a mortgage 'earns' its interest rate. We show with numbers when investing, an emergency fund or paying off other debt makes more sense.
Overpaying a mortgage: shorten the term or lower the installment? Overpaying your mortgage? We compare a shorter term, a lower installment and the snowball method: the interest each saves and when to choose which.
Buy a flat or rent? Buying or renting? Why 'rent is money down the drain' is a myth, what really decides the result and how to compare both on your own numbers.

Saving and inflation

EDO or COI? Which Polish treasury bonds to choose EDO, COI and TOS from this month's offer compared: after-tax returns at different inflation rates, early redemption fees and when each one pays off.
Treasury bonds or a bank deposit — which pays more? A bank deposit or Polish treasury bonds? After-tax returns at this month's bond offer and the NBP rate, plus risk, access to your money and inflation.
The Belka tax — how it works and how to avoid it legally The Belka tax is Poland's 19% tax on interest and investment gains. How it's charged on deposits, bonds and ETFs, and the legal ways around it.
Inflation and your savings: what you really lose What is 1,000 zł from 2010 worth today? GUS data shows how inflation eats savings, how to work out a real return and what protects money from inflation.

Investing and retirement

IKE or IKZE — which one to choose? IKE or IKZE? Contribution limits, the tax relief, the tax on withdrawal and a comparison in numbers for different incomes — and when to have both.
Is PPK worth it? PPK in numbers: what your employer and the state add, the tax you pay on it and what's left if you withdraw early. When opting out makes sense.
The 4% rule — how much do you need for FIRE? The 4% rule tells you how much capital lets you live off your investments. Where it comes from, what it assumes, how to adapt it for Poland and how long it takes.
Compound interest — how it works and why time matters Compound interest in practice: the formula, examples over 10, 20 and 30 years, the rule of 72 and the effect of fees, the Belka tax and inflation.

How the calculators work

All calculations run in your browser — the amounts you enter are never sent anywhere. Each calculator page explains the formulas it uses and walks through an example. The calculation logic is covered by automated tests.

How we prepare our guides

The numbers in our guides come from our calculators and from official data: the Ministry of Finance's treasury bond offer, inflation from GUS (Statistics Poland), the NBP reference rate and the rules in force, such as the IKE and IKZE contribution limits. The examples are worked out with the same code as the calculators, and the buttons next to them open the calculator with the same numbers, so you can check and change every result.
When GUS, the NBP or the Ministry of Finance publish new data, the guides are recalculated automatically — together with the conclusions that depend on those numbers — and the date under the title changes.
At the end of each guide we list our sources: the laws and the official pages the rules we describe come from.
The guides are for educational and informational purposes. They are not financial, investment or tax advice: they show how to work out a decision and what the result depends on, but they don't know your situation.
Spotted a mistake or something out of date? Write to us: kontakt@liczymyfinanse.pl

Assumptions and limitations

In the calculators that look ahead, interest rates, returns and inflation are constant for the whole period. In reality they change, so a result is a scenario, not a forecast. For past years the inflation calculator uses actual GUS data.
Results are before fees, except the treasury bonds calculator, which deducts early redemption fees, and the buy-or-rent comparison, which deducts the costs of buying and selling the home. Capital gains tax (19% in Poland) is included in the compound interest, treasury bonds and bank deposit calculators and in the overpay-or-invest and buy-or-rent comparisons — the latter also charges the 19% tax on selling a home within five years of the end of the purchase year. The bank deposit calculator deducts the tax on interest at every capitalisation, rounded to the grosz, as banks do. The IKE, IKZE and PPK calculator applies each account's tax on withdrawal, the IKZE tax refund and the income tax on the employer's PPK contributions, but leaves out account and fund fees. The FIRE calculator does not deduct tax. The mortgage calculators ignore fees and insurance.
The default 3.5% inflation is roughly the average annual CPI inflation in Poland in 2010–2025, according to Statistics Poland (GUS). The default 7% return is the historical nominal average for a diversified global equity portfolio. The treasury bonds and bank deposit calculators default to the latest GUS inflation figure, and the treasury bonds calculator takes its rates from the Ministry of Finance's current offer. The default loan rate in the mortgage overpayment and overpay-or-invest calculators (the NBP reference rate plus a 2 percentage point margin) and the default deposit rate (the reference rate itself) come from the current NBP reference rate. The inflation calculator uses GUS's monthly price indices since 1991. All of this data is updated automatically when the sources publish new data.

Privacy

We do not use cookies. Visits are counted anonymously with Umami, which stores no visitor identifiers and never receives the amounts you enter. Calculator inputs only go into the page address in your browser, which is how you can share a result with a link.

Disclaimer

The calculators are for educational and informational purposes. They are not financial, investment or tax advice, nor a recommendation within the meaning of any law. Before an important decision, check your contract terms or talk to an adviser.

Contact

Have a question, spotted a calculation error or missing a calculator? Write to us: kontakt@liczymyfinanse.pl