What is WIBOR and how does it affect your installment?
WIBOR is the reference rate behind most variable-rate mortgages in Poland. A simple explanation with an example.
Kready · 2026-08-24
WIBOR (Warsaw Interbank Offered Rate) is an interest rate index that reflects the cost of money between banks. For mortgages the 3-month (WIBOR 3M) or 6-month (WIBOR 6M) index is used.
How it builds your rate
Your rate = bank margin + WIBOR
Example (September 2026): margin 1.8% + WIBOR 3M 3.84% = 5.64%.
The margin stays the same for the whole loan (unless your contract says otherwise). WIBOR changes – with it, your installment.
How often it changes
- 3M: the rate is updated every 3 months,
- 6M: every 6 months.
A 6M index reacts more slowly – in both directions.
What moves WIBOR
Mainly the National Bank of Poland's reference rate and market expectations about it. In 2026 the NBP rate stands at 3.75% after one cut in March.
The reform
A reform of reference rates is underway in Poland, planned to replace WIBOR with a new index. Existing contracts will be switched by law; your bank will inform you.
How to protect yourself
- choose a periodically fixed rate,
- keep a financial cushion of several installments,
- consider overpaying when rates are low.
The calculator uses current WIBOR values updated by our team.