Placekey Design

Each Placekey is divided into two parts: What and Where, written as “What@Where”. The What part encodes information about the place and its address, while the Where part situates that place on Earth. The What part of a Placekey is optional, and a What-less Placekey like “@5vg-7gq-tvz” refers to a region on the Earth while a What part plus a Where part specifies a particular place within a region on the Earth.

The Where part of a Placekey encodes a hexagon of approximately 15,000 m² on the surface of the Earth. These hexagons have an edge length of 66 m on average, and it can be helpful to think of them as roughly circles with a diameter of 132 m. The exact area and edge length of the hexagon varies by location. In particular, these hexagons are given by resolution 10 H3 indices.

The What part of a Placekey encodes an address (when it is just about an address) or an address and a POI (when a POI is present). What parts are only unique up to the Where part of a Placekey.

The What part exists in two styles, both fully valid:

• Style 1: A compact numeric format like 227-223@5vg-82n-pgk. Older Placekey'd POIs use this style.

• Style 2: A longer alphanumeric format like 1vqew7z3sv@5vg-7gq-tvz. Newer POIs use this style.

In Style 2, encodings that start with 0 refer to addresses (e.g., 03ho5zb3wz@5vg-7gq-tvz) and those that start with 1 refer to a POI (e.g., 1vqew7z3sv@5vg-7gq-tvz). Both styles are returned by the API and should be treated as opaque strings for matching purposes.

More details on the design of Placekey can be found here.