What a PLZHub estimate means
When you see an estimate flag on PLZHub, it means the underlying data in data/plz_master.json isn't a direct one-to-one match. We had to weight or derive the numbers. You'll notice this mostly with mixed postcodes like 1008 Prilly or 1040 Echallens.
Take 1008 Prilly. The postcode boundary cuts right through the middle, splitting the area between Prilly and Jouxtens-Mézery. At 1040 Echallens, three different municipalities share the postcode, each taking about a third.
In these situations, the tax.isEstimate and demographics.isEstimate flags aren't just technical footnotes. They tell you exactly what you're looking at: a solid approximation, not the hard numbers for a single municipality.
When the flags matter
If tax.isEstimate is true, you shouldn't treat the tax figure as absolute. The demographics.isEstimate flag does the same job for population, household counts, and age brackets.
You need to watch these flags when you're comparing two locations. It helps to know if you're looking at direct data or an approximation. For instance, 1000 Lausanne 25 has an estimated tax figure, but its demographic data is direct. We flag this clearly because we'd rather be upfront about how the numbers are built than pretend everything is perfect.
When to worry less
You don't need to stress over every estimate. Look at 6052 Hergiswil NW. The neighboring municipality of Horw creeps in, but only covers 0.199% of the mix. We still trigger the estimate flag because that's technically correct, but in practice, you can ignore it.
1468 Cheyres sits at the other end of the scale. Both flags are off because the postcode maps directly to the municipality.
The short version
Treat mixed postcodes as guides, don't overthink the tiny edge cases, and trust the direct matches. That's the whole point of the flags—they help you filter locations quickly without giving you a false sense of precision.
