Rapid Addressing

Put in the postcode - Get the address

Address Management

Rapid addressing; postcode identification and more

Mailing List Generation

Build mailing lists for bulk mailing for free

Web Use

Get addressing and location data online

Map referencing

Locate addresses on a map

Where's My Nearest?

Find the local branches of a business

Mobile Use

Deployment on mobile devices

Map Referencing

A very common requirement is to find out where an address or postcode is on a map.

The opposite requirement is also sometimes needed - that is, given a map reference to find addresses at or near that point.

Postcode-level vs Premise-level positioning:

Map references are available for the centres of postcodes (postcode-level) and for the centres of properties (premise-level). On average, a postcode covers 17 premises, so a positioning on this basis is generally very close to a particular house and is adequate for many applications.

For certain applications, the more accurate premise-level positioning is required.  The illustration below shows an example of a road in which there are are about 20 houses on each side and a postcode for each side.

Road level + Premise level

Postcode-level and premise-level location referencing.

Arc en Ciel obtains map reference data from the Ordnance Survey, the premier mapping agency for Great Britain, and the Ordnance Survey for Northern Ireland This is generally accurate to ±1 metre.

Premise-level data is considerably more expensive than postcode-level and has restrictions on use. It forms part of our mailing-list generation application AddressList.

Our Address and Address+ products use postcode-level data which is normally used by developers through the API.

Postcode-level data is also returned by our webservice. In this case a postcode is sent to our server and a map reference, and other ancillary data, is returned. This service is sold in blocks of 10,000 lookups and is widely used to service websites.


Geo-referencing is the term used to define the form in which map references are provided. A very convenient form is the Ordnance Survey grid reference.  In this case a nominal origin off the Scilly Isles is defined and references are given in Cartesian coordinates in metres.

For example, the grid reference (529552,180646) is a point 529.552km east of Scilly and 180.646km north and locates Piccadilly Circus.

For some purposes latitude and longitude, although more difficult in use, are more accurate and critically provide continuity across national boundaries. The reference 0°8' 4" W, 51°30' 35" N again locates Piccadilly Circus.

There are many slightly different ways of calculating latitude and longitude. Arc en Ciel uses the WGS84 system which is compatible with satnav devices. We can provide software to developers to convert this into the systems traditionally used in Great Britain and Ireland.

A more recent system of geo-referencing is provided by What3Words. Here, the earth is divided into 3m x 3m squares and each square is uniquely referenced by three words. An example is shown below.


What3Words geo-referencing.

Some believe that what3words or a similar system will replace conventional postal codes in many situations.  In fact the country of Ivory Coast has adopted the system for its own postal service. Again, Arc en Ciel can provide software to convert to this system.

Postcode from position:

You may have a position and need to find an address. For example, a GPS device in a vehicle can send longitude/latitude and from that the closest address can be found. As part of its Developers' API Arc en Ciel provides a function CodesInRadius which finds the postcodes within a given radius of a point. The nearest postcode can be found and used to generate the address.

Position from place name:

If the user does not know a postcode - say they are looking for a property in a certain town - then our Gazetteer product which gives map references for the centre of over 12,000 towns, villages and localities is the best way forward.