How Swiss postal codes work
A postal code is not a place. It is a sorting key, introduced by Swiss Post in 1964 to move letters through the country faster — and everything else about it follows from that single purpose. Once you know that, it stops being surprising that a postal code so often cuts across municipal boundaries.
What the four digits mean
The four positions were never arbitrary. They read from the outside in:
- The first digit marks a large routing region.
- The second narrows it down within that region.
- The third originally stood for the rail route the item travelled on. That meaning is long gone; the digit stayed.
- The fourth identifies the specific delivery point.
The third digit is the most interesting part: it is a leftover from a logistics system that no longer exists. The scheme carries its own history around with it.
From 1000 to 9658
The numbering runs geographically from west to east. The lowest code in use is 1000 Lausanne, the highest 9658 Wildhaus. So the first digit of any Swiss postal code tells you roughly which part of the country you are in — a 1 puts you in the French-speaking west, a 9 in the east.
There are 3'190 postal codes in use today.
Why a postal code is not a boundary
This is the heart of it. Postal codes follow delivery routes, not political borders. A postal round ends where it is practical to end, not where a municipality stops.
The consequence is measurable: 1'223 postal codes cover more than one municipality — 38.3% of all codes. The reverse holds too: plenty of municipalities carry several postal codes. A postal code is therefore never a reliable stand-in for a municipality, which is the subject of why a postal code is not a municipality.
The edge cases that explain the system
Exceptions often explain a system better than the rule does:
- Kefikon sits across two cantons and carries two codes: 8543 Kefikon ZH and 8546 Kefikon TG. One place name, two postal codes, because the cantonal border runs straight through it.
- La Cibourg goes further: the hamlet spreads across several municipalities and two cantons, and appears under three postal codes — 2300, 2333 and 2616.
- The Jungfraujoch has its own code, 3801, despite almost nobody living there. What matters to the post office is not population but whether deliveries happen.
- 3823 covers several high-alpine points at once, among them Eigergletscher and Kleine Scheidegg — a code that maps a railway line rather than a settlement.
Postal codes change
The system is not frozen. Municipalities and cantons can ask Swiss Post for new codes, and that happens especially after municipal mergers, when several municipalities each holding their own code become one.
Which is exactly why a postal code makes a poor permanent identifier. To identify a municipality reliably over the years you need the BFS number — it stays put even when the name and the postal code do not.