Kantor is the Polish word travellers quickly learn from glowing exchange boards. The board normally gives two prices for each foreign currency because the business buys at one rate and sells at another. The space between them is the spread, and it can matter far more than a sign promising zero commission.
Read the board from the bureau's chair
Turn the displayed rate into one concrete question
Board order has fooled real customers
Polish consumer-protection authorities have taken action against bureaux that reversed the expected buy/sell column order. Customers focused on an attractive left-hand figure and received far fewer złoty than expected. Column headings and the final cash total matter more than position or font size.
Zero commission can still hide an expensive spread
A bureau can charge no separate fee while buying your currency well below the market reference. Use the NBP reference rate as orientation, not a retail promise, then compare how many złoty each option actually delivers after every fee and spread.
Airport convenience is a different product
Stations, airports and border crossings often keep longer hours, but a convenient location can support a wider spread. Exchange only the amount needed for the immediate journey when the rate is weak, then compare city options in daylight rather than searching with luggage late at night.
Count before leaving the counter
Check the receipt, denomination mix and cash while still in view of the cashier. Ask for smaller notes if a stack of 200s or 500s would be difficult to spend. Once a valid exchange is completed, Poland Travel warns that a kantor transaction cannot simply be reversed because the customer dislikes the rate.
The card screen has its own hidden kantor
Dynamic currency conversion at a terminal or ATM is another exchange offer. The same discipline applies: compare the final markup, reject a poor home-currency conversion and keep the transaction in PLN when your own card offers the better route.