Shorten Plus Code

Open Location Codes, better known as Plus Codes, turn latitude and longitude into short strings that people can speak, type, and print without street numbers. A full code such as eight F V C nine G eight F plus six X is globally unique, but most everyday sharing happens inside a known city or neighbourhood, where the leading pairs repeat and only the trailing block identifies the spot. This Plus Code shortener accepts a valid full code plus a nearby reference latitude and longitude, measures how close the reference is to the code centre, and drops as many leading character pairs as the Open Location Code safety rule allows.

How Plus Code shortening works relative to a reference location

A full Open Location Code encodes a rectangular cell on the Earth using the twenty-character alphabet two through nine and C F G H J M P Q R V W X, with a mandatory plus separator after eight characters. The first ten significant digits form latitude and longitude pairs that refine the cell by successive factors of twenty; optional grid digits after the separator refine further.

When you share a location inside a known area, the first four or six characters often match every nearby place, so they add noise rather than value.

Shortening does not simply strip a fixed prefix: it decodes the full code to its cell centre, compares that centre to your reference latitude and longitude with a Chebyshev metric (the maximum of absolute latitude difference and absolute longitude difference in degrees), and walks a fixed resolution table of twenty, one, zero point zero five, zero point zero zero two five, and zero point zero zero zero one two five degrees.

Whenever the range is less than thirty percent of a given pair resolution, the algorithm may drop the corresponding leading pairs. That thirty percent factor is a deliberate safety margin so the short code remains the nearest match when someone later recovers it from a slightly different city centre or GPS reading. If the reference is far away, no pairs are removed and the full code is returned unchanged.

Padded codes that only describe a large area (with zeros before the separator) cannot be shortened, because they lack enough precision digits to trim safely. The capability implements this pure arithmetic path only: it does not look up place names, call maps APIs, or invent locality labels you should append yourself.

Where a Plus Code shortener earns its keep

Delivery, field-service, and logistics apps already store full Open Location Codes for doors that lack street numbers; when they print a label or send an SMS inside a known city they need the short form that drivers already recognise from Google Maps and plus.codes. Disaster-response and humanitarian mapping workflows share temporary shelters and water points as short codes plus a camp or district name, and a deterministic shortener guarantees every client—mobile offline pack, edge worker, or spreadsheet import—agrees on the same trim for the same reference.

Developers integrating OLC into forms can validate and shorten in one call without shipping a full open-location-code library to every client. Failed validation does not consume balance.