We usually think of a postcode as a neat, tidy box. But in Switzerland, borders get messy. A single postcode often spills over into two, three, or even seven different municipalities. The clearest examples on PLZHub are places like 1008 Prilly, which splits straight down the middle between two communes, or 1040 Echallens, which fragments into several tiny pieces.
In these situations, the postcode is a great tool for delivering mail or narrowing down a search map. But if you try to use it to figure out your taxes or your kids' school district, you will end up with the wrong answer.
The trickiest examples are often the ones that look completely ordinary. 1008 Prilly sounds like one place, but it's a perfect 50/50 split between Prilly and Jouxtens-Mézery. 6110 Wolhusen is heavily dominated by one municipality, but the postal boundary still drags in addresses from six others. Even 1148 Chavannes-le-Veyron, which looks like a single-municipality postcode, quietly carries tiny cross-border address fragments.
What "weighted share" actually tells you
When you look at municipalities.weightedSharePct in our data, you are looking at the share of physical addresses inside that postcode that belong to each municipality. It is a strict count of front doors and letterboxes. It is absolutely not a population headcount, and it is definitely not an official legal border.
Because Swiss geography is complicated, a postcode's address weight can look very different from place to place:
- It can be a clean coin flip, like
1008 Prilly. - It can be dominated by a heavy favorite, like
6110 Wolhusen. - It can be 97% pure but still technically split, like
1148 Chavannes-le-Veyron. - It can scatter across a long tail of rural fringe borders, like
9107 Urnäsch.
When to stop trusting the postcode
As soon as you see a postcode splitting near 50/50, or if you spot three or four different municipalities sharing the same number, you have to stop treating that postcode as a single administrative unit. It isn't one.
At that point, if you are looking at tax rates, voting districts, or building permits, you must look at the exact municipality instead. The postcode has done its job by getting you to the right general area.
Just to keep things interesting, the exact opposite scenario exists too. Take 1000 Lausanne 25. It proves that multiple named localities can easily sit inside a single municipality. You simply cannot rely on the postal label alone to settle an administrative question in Switzerland.
