What Are Plus Codes (Open Location Code)?

Plus Codes are the commonly used name for Open Location Code (OLC), an open method of turning latitude and longitude into a short code. A code names a small rectangular area, and the more characters it has, the smaller the area. The system was designed so that places without street addresses can still be given a compact, shareable reference.

What a code looks like

A full code is written in two parts separated by a plus sign, for example 8FVC9G8F+6W. The characters before the plus sign narrow the area step by step, and the characters after it give the final refinement. The characters come from a 20-symbol alphabet that avoids vowels and some similar-looking letters, which reduces the chance of forming words and of confusing characters.

Short codes

Because a full code is long, people usually write the last part and add a nearby town or city: 9G8F+6W Zurich. The software works out the missing first digits from the named locality. This makes everyday sharing easier but depends on the locality being recognised correctly.

How the area shrinks

Each pair of characters divides the previous area into a grid. A code with 10 characters in total (before and after the plus sign) identifies a cell of roughly 14 metres by 14 metres, since the cell is 1/8000 of a degree on each side. Adding one more character divides that cell again into a grid of smaller cells, down to a few metres. The number of decimals involved is comparable to what is shown in the decimal places guide.

Strengths

• Open and free to implement: published specification, with libraries in many languages.
• No data needed to decode: the code is a direct mathematical encoding of coordinates, so it does not require a lookup database.
• Supports shorter forms: with a locality, a code can be written briefly.
• Works anywhere on Earth: no dependence on street data.

Limitations to consider

• A standard code is about 14 m wide, which is larger than a doorway or a pedestrian entrance.
• It is not a postal code and is not issued by postal authorities.
• Short codes need a reference locality to be read back correctly.

Comparison with other approaches

Plus Codes are one of several grid-based designs, alongside geohash, MGRS and word-based systems. They differ in their alphabet, their cell sizes and the audience they were designed for. UPCS codes use a different format, CC-XXXX-XXXX with a two-letter country prefix, for a 3 m by 3 m cell, and are meant to accompany a normal address. See how location codes are generated from coordinates for the general idea.