Kosaki postal code
Village · łomżyński county (powiat) · Piątnica municipality (gmina) · podlaskie voivodeship
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The postal code for Kosaki is 18-421.
Postal code – Kosaki
How to address a letter or parcel in Poland?
Jan Kowalski Kosaki 15 18-421 Kosaki
Write the postal code in the 00-000 format on the last line, before the town name. Put the recipient's full name on the first line and the street with building and flat number on the second. For mail from abroad, add POLAND as the final line. There are no named streets in Kosaki, so the second line contains the locality name and property number (e.g. Kosaki 15). If the serving post office is in another locality, its name can appear next to the code on the last line.
Frequently asked questions
How do I address a letter to Kosaki if it has no named streets?
Instead of a street, write the locality name and house number, e.g. “Kosaki 15”. On the last line, write the postal code 18-421 and the locality or post office name.
What is the postal code for Kosaki?
The postal code for Kosaki is 18-421.
Which voivodeship and county is Kosaki in?
Kosaki (village) is in łomżyński county (powiat), Piątnica municipality (gmina), podlaskie voivodeship.
Which localities are closest to Kosaki?
The closest localities to Kosaki are: Podkosacze (1.4 km), Nowe Krzewo (2.1 km), Krzewo (2.5 km), Truszki (2.5 km), Bronowo (2.9 km), Żelechy (3.2 km). Distances are measured in a straight line between locality centres.
Localities near Kosaki (łomżyński county)
Which county and municipality does Kosaki belong to?
Kosaki lies in Piątnica municipality (gmina), in łomżyński county (powiat), podlaskie voivodeship, Poland. Centre of the area based on address points: 53.1533, 22.2664.
Where does this data come from?
Localities and postal codes come from the public TERYT registers (Statistics Poland), while streets, building numbers and locations come from the National Register of Boundaries (GUGiK). Data as of 12.11.2026. This site is not affiliated with Poczta Polska; for important shipments, confirm the code at a post office. More about sources