Swiss municipality number
The number identifying a Swiss municipality in the official municipality register kept by the Federal Statistical Office.
The BFS number is the key of the official Swiss municipality register, which held 2,110 municipalities at the start of 2026.
One to four digits, published without padding: Aeugst am Albis is 1, Bachenbuelach 51, Aarberg 301, Aadorf 4551. It is a flat serial rather than a composite, so the canton cannot be read from it. The often-repeated claim that the number begins with a canton number is wrong, and the canton is a separate field in the register.
Numbers run to 6831 with wide gaps, because each canton holds a reserved block. Padding a value to four digits produces something the register does not contain, and a four-digit number is easy to confuse with a postal code, which the Swiss data-exchange standard warns about directly.
That standard also states that a number released long ago may in rare cases be issued again. A rename leaves the number alone; a merger or a split does not.