What the resolution buys
The gain is not precision for its own sake — it is that postal codes are small enough to be internally consistent. A region averages over areas that differ enormously; a postal code usually does not.
- Germany — roughly 8,200 five-digit postal codes, small enough that one typically covers a district or a few villages.
- United States — roughly 41,000 ZIP codes, though these are mail routes rather than areas, which has consequences below.
- United Kingdom — postcode sectors and units go finer still, down to a handful of addresses at unit level.
Where it is worth the effort
- Physical catchments — a store, branch or venue draws from a defined area, and regional targeting wastes most of the budget outside it.
- Direct mail and door drops — bought by postal code by definition.
- Out-of-home — placement is inherently a point on a map.
- Test and control design — matched sets of postal codes make clean regional experiments possible, which is what turns a campaign into a measurement.
- Sponsorship geography — checking whether a property's audience sits inside a sponsor's distribution footprint.
Where it breaks down
- Postal codes are administrative, not behavioral. They were drawn for delivering mail. A genuine catchment routinely straddles several and splits one.
- US ZIP codes are routes, not polygons. Treating them as areas introduces error that varies by region, and a ZIP can cover a single building or hundreds of square kilometres.
- Small units mean small numbers. Audience estimates at postal-code level rest on fewer observations and are correspondingly less stable. Aggregating adjacent codes is usually more honest than reporting each one.
- Not every channel can buy it. Broadcast and much national inventory cannot be bought below regional level, and a postal-code plan that no channel can execute is an analysis, not a plan.
The useful discipline: plan at postal-code resolution, then aggregate up to the smallest unit the chosen channel can actually buy. The resolution informs the decision even where it cannot be executed directly.
How Rascasse provides it
Audience concentration is resolved to postal-code level in the built-out markets, derived from behavioral signals rather than from modelled purchasing power — which means it reflects interest in a specific brand or category rather than the general structure of an area.
In the product
Postal-code-level audience selection sits in Places.
Related terms