How does a bank calculate borrowing capacity?

The bank deducts living costs, other loan instalments and the burden of card limits from your net income. What is left is the maximum instalment - but it is further capped by the DSTI ratio, the maximum share of all instalments in your income (usually 40-50%). From the maximum instalment the bank works out the loan amount, but not at your interest rate - at your rate plus a buffer of at least 2.5 percentage points.

DSTI (Debt Service to Income) is the share of all your loan instalments in your net income. If you earn PLN 12,000 and pay PLN 4,800 in instalments in total, your DSTI is 40%. Banks in Poland usually don't go above 50%, and at lower incomes they go down to 40%.

Why does an unused credit card reduce my borrowing capacity?

Because the limit counts, not the balance. You may owe nothing on the card, but since you could spend PLN 20,000 tomorrow, the bank treats it as a potential liability and adds about 3% of the limit a month as a burden. A card with a PLN 20,000 limit looks to the bank like a PLN 600 monthly instalment - even if it sits in a drawer.

What improves borrowing capacity the most?

Closing credit cards and overdraft limits, paying off small loans and 0% instalment plans, extending the loan term, adding a co-borrower with an income, and a larger down payment. Extending the term works fastest, but costs the most in interest - there is no free lunch.

Is borrowing capacity the same at every bank?

No. Every bank has its own scoring model, its own living cost tables and its own approach to sources of income. Differences in calculated capacity between banks can reach 30% for identical applicant data. That is why it is worth checking several offers instead of going to the first bank you come across.

Calculator

Borrowing capacity

Q: Why does the bank calculate capacity at a higher interest rate than the real one?

It is required by Recommendation S of the KNF (Polish Financial Supervision Authority). The bank must check whether you could handle the instalment even if interest rates rise. That is why it adds a buffer of at least 2.5 percentage points to the interest rate. The effect: at a 7.5% interest rate, capacity is calculated as if the loan cost 10%. This cuts capacity by somewhere between ten-odd and twenty-odd percent.

How much a bank will really lend you - not what you would like to hear. We calculate it the way banks do: with the interest rate buffer required by the KNF (Polish Financial Supervision Authority) and with the DSTI limit. And we show the whole calculation, step by step, so you know exactly what is eating into your capacity.

Household net income i

PLN

Living costs i

PLN

Leave it at PLN 0 and we will estimate costs from the social minimum based on the number of people in your household.

People in household

ppl

Other loan instalments i

PLN

Card and overdraft limits i

PLN

Loan interest rate

Loan term

yrs

Down payment i

PLN

Estimated borrowing capacity

Maximum instalment i

Instalment you will actually pay i

Maximum property price

DSTI ratio i

Where this comes from

The bank doesn't guess. It deducts item after item from your income and looks at what is left. Here is the same calculation, line by line.

Item	Monthly amount

From the maximum instalment the bank works out the loan amount - but not at your interest rate, at the interest rate with the buffer:

Step	Value

Where your income goes

Living costs

Other instalments and cards

New loan instalment

Money left over

Longer term = higher capacity. And a much higher cost.

Borrowing capacity

Total interest to pay

Term	Capacity	Instalment	Total interest	Interest / loan amount

This is an estimate, not a credit decision

This calculator reproduces the logic banks use - not their specific model. Every bank has its own scoring, its own living cost table and its own approach to sources of income. Differences in calculated capacity between banks reach 30% for identical applicant data.

Treat the result as a reference point and check several offers instead of going to the first bank you come across.

Explanation

How a bank really calculates capacity

Contrary to what the adverts suggest, borrowing capacity is no secret. It is arithmetic with a few catches. The catches matter more than the arithmetic.

Step 1: how much you have left

The bank takes the net income of the whole household and deducts from it, in turn: living costs, instalments on existing loans and the burden of card and overdraft limits. What is left is the surplus - the pool from which a new instalment can be paid.

Watch out for living costs: you can declare that the two of you live on PLN 1,500 a month, but the bank will substitute its own table anyway. It is usually a version of the social minimum - around PLN 1,200 for the first person and PLN 800 for each additional one, often adjusted for the cost of running the property.

Step 2: the DSTI limit

Even if you have plenty of money left after deducting everything, the bank still won't let instalments swallow any share of your income it likes. They are capped by the DSTI ratio - Debt Service to Income:

DSTI = sum of all instalments ÷ net income

≤ 40% - safe, accepted by every bank
40-50% - upper limit, usually accepted at higher incomes
> 50% - an almost certain refusal

Our calculator assumes DSTI = 50% and takes the lower of the two limits: the surplus and the DSTI limit. With an income of PLN 12,000 and costs of PLN 3,000 the surplus is PLN 9,000, but the DSTI limit cuts the instalment to PLN 6,000. It is DSTI that binds, not living costs.

Step 3: the +2.5 pp buffer - the catch nobody talks about

This is the heart of it. The bank does not convert the maximum instalment into a loan amount at your interest rate. This is required by Recommendation S of the Polish Financial Supervision Authority (KNF): the bank must check whether you could handle the instalment even if interest rates rise. That is why it adds a buffer of at least 2.5 percentage points to the interest rate and only then calculates your capacity.

What the buffer costs

An instalment of PLN 6,000, a 25-year term, an interest rate of 7.5%: if the bank calculated it directly, it would lend you PLN 811,918.

But the bank calculates at 10% (7.5% + a 2.5 pp buffer) - and gets PLN 660,283. The buffer took away PLN 151,634 of capacity, nearly 19%.

This isn't the bank being spiteful, it is a lesson from 2021-2023, when WIBOR went from 0.2% to over 7% and loan instalments rose by tens of percent within a year or so. The buffer is a test: would you survive if it happened again.

You pay the instalment, however, at the real interest rate - the buffer is only used to work out the amount. That is why you see two different instalments in the results, and it is not a mistake.

Credit card: a PLN 20,000 limit = a PLN 600 instalment

The most unfair - and most underestimated - item in the whole calculation. The bank looks at the limit granted, not at how much you actually owe.

The logic is simple: since you could spend the whole limit tomorrow, it is a potential liability. Banks usually count 3-5% of the limit a month as a burden. A card with a PLN 20,000 limit that has been sitting unused in a drawer for two years looks to the bank like a PLN 600 instalment every month.

What it does to your capacity

With our default data, a card with a PLN 20,000 limit cuts capacity from PLN 660,283 to PLN 594,255. It costs you PLN 66,028 of loan - for a product you don't use.

The practical takeaway: close your cards and overdraft limits 2-3 months before applying (that is how long it takes for the record in BIK, Poland's credit bureau, to update). It is one of the cheapest things you can do for your capacity.

What improves capacity

Closing cards and overdraft limits. The effect is immediate and free. Every PLN 10,000 of limit is about PLN 300 of "instalment" to win back.
Paying off small loans and 0% instalment plans. Instalments for a phone or a TV are also recorded in BIK and also lower your capacity.
Extending the loan term. Works fastest, but costs the most - see the chart above. Capacity grows more and more slowly, while interest grows in a straight line.
A co-borrower with an income. Adds income and usually few costs - the most effective single move. But it also means shared responsibility for the debt.
A larger down payment. It doesn't raise capacity directly, but it reduces the loan amount you need and lowers the bank's margin - with a down payment of ≥ 20%, margins are noticeably lower than at 10%.
Stable, documented income. A permanent employment contract is the gold standard. Three months with your current employer is the typical minimum.

What damages it

Payday loans in your BIK history. Even if repaid on time. For scoring it is a signal that you were short of money for day-to-day expenses in the past. Some banks reject the application automatically.
Contracts for specific work and civil-law contracts (umowa o dzieło / zlecenie). Banks usually accept 50-80% of such income and require a longer history (often 12 months).
Credit cards and revolving limits. See above - the limit counts even with a zero balance.
Late payments. 30 days in arrears recorded in BIK can close the door to a mortgage for several years.
Too many credit enquiries at once. Applying to ten banks in a week looks like desperation in BIK.
A recent change of job. A probation period or your first month at a new company is a stop for most banks.

Three things to remember

1. Capacity is calculated at a higher interest rate than the real one - the KNF buffer takes away about 15-20% of the amount.
2. An unused credit card costs you real tens of thousands of zloty in capacity. Close it before you apply.
3. A longer term raises capacity, but at 30-35 years interest can exceed the amount of capital borrowed.

Frequently asked questions

Will the bank show me its calculation?

It doesn't have to and usually doesn't. The scoring model is a trade secret. You get a decision and an amount - with no breakdown. That is why it is worth understanding the logic in advance, so you know where to look for headroom.

I am self-employed. How is my income counted?

Banks usually take into account net income (revenue minus costs minus tax), averaged over the last 12 months; for flat-rate taxation (ryczałt) often with their own conversion factor. Enter that averaged income in the calculator, not the revenue from your invoices.

Do 500+ (the Polish child benefit) and other benefits count as income?

It depends on the bank. Some count child benefits in full, some partly, some not at all - and at the same time every child raises the assumed living costs. The net effect is often neutral or even negative.

Why did two banks give me completely different amounts?

Because they have different cost tables, different DSTI thresholds (40% vs 50%), different approaches to sources of income and different buffers (the KNF requires a minimum of 2.5 pp - some banks apply more). A 30% spread is normal, not an anomaly.

Is it worth taking the maximum amount the bank offers?

Almost never. Maximum capacity is the limit at which the bank believes you will just about cope - not the amount at which you will live comfortably. An instalment at 50% of your income means living with no margin for a car breakdown, illness or losing your job. A sensible ceiling is DSTI below 35-40%.

How long is a capacity assessment valid?

A bank's credit decision is usually valid for 30-60 days. After that the bank recalculates everything from scratch - and interest rates, your income and liabilities may have changed in the meantime.

You know your capacity. Now find the cheapest offer.

Capacity tells you how much you can borrow. APR tells you what it will really cost you. See the logic the bank uses to calculate your capacity - and what you can improve before you apply.

How banks calculate capacity Apply