Regional Statistics
Population in Sejny Municipality 2026
Sejny municipality ranks 2115 of 2,478 Polish municipalities. Population shrank by 229 residents -5.71% between 2019-2024, now at 3,778.
Among 1984 declining municipalities, in bottom 50% for rate of decline. Within Sejneński county, ranks 3 of 5 municipalities.
Based on 31 years of official GUS statistics for Sejneński county municipalities within Podlaskie voivodeship.
Popular Cities in Poland
You may also be interested in
Contact Information for Sejny
Updated 28 days ago
Top tools
Polish IBAN Generator
Generate a valid Polish IBAN from a bank code and account number. See the 28-character PL IBAN format with a real example.
Mikrorachunek Checker
Check whether a mikrorachunek podatkowy number matches the official format and extract the embedded PESEL or NIP.
REGON Number Checker
Check any 9-digit or 14-digit Polish REGON number with automatic format detection and checksum verification.
Top articles
NIP Number in Poland: How to Find, Check, and Validate It
What is a NIP number in Poland? Learn how to find your own NIP, check a company's tax ID, and validate any Polish NIP online.
7 min readPoland Business Registry Search: How to Look Up a Company by NIP
Look up any Polish company by its NIP number. Search CEIDG, KRS, and the VAT white list to verify businesses and confirm VAT status.
7 min readHow to Pay a PIT Underpayment in Poland
Owe money after filing your PIT in Poland? Learn how to pay a niedopłata step by step, including deadlines, transfer details, and late payment interest.
8 min readLet's build Poland.gg together
Join our Discord community. Get early access, shape the roadmap, and connect with data people across Poland.
Dashboard and business tools go public in 2027 — early supporters access them first and keep their discount on everything.
Get up to 90% off — forever
The longer you stay, the less you pay. 9% off per month, stacking up to 90%. The 100 longest supporters get free access for life.
© 2026 Poland.gg