Postcode Structure

One of the most common questions we get asked is "How is a Postcode Structured?". Understanding the different levels of Postcode and what they mean will make using Postcodes for planning in your business a lot easier.

The UK Postcode system is essentially made of 3 levels of Postcode boundaries. Whilst initially developed to ensure optimum delivery of mail, the Postcode system has proved to be a highly effective and popular way of defining geographic areas across the UK for the following reasons:

1. The system is tiered allowing you to use Postcodes to view related data at a very local level (100 metre accuracy    using the full Postcode) through to a national level using Postcode Areas.
2. Postcode boundaries nest into each other - all postcode Sectors fall into the correct Postcode District which fall into their parent Postcode Area.
3. Postcodes provide contiguous and complete coverage of the United Kingdom
4. The Postcode is recognised by almost everybody in the UK. Ask someone their Postcode and they will invariably know it, ask them their enumeration district (for example) and you are likely to be met with a confused gaze. This makes it a great framework for collecting and analysing consumer and business data.

Today, the Postcode system is widely used for business applications such as sales territory management, retail catchment analysis, media coverage and market assessment. So what are the different levels of the Postcode Structure? The table below describes them in more detail.

Postcode Area

A Postcode Area is the first 1 or 2 letters of the Postcode (e.g. UB from UB7 0EB). There are 124 Postcode Areas covering the UK from AB to ZE. Postcode Areas are ideal for general national mapping and analysis.

Postcode District

A Postcode District is the first half of the Postcode (e.g. UB7 from UB7 0EB). There are approximately 2,800 Postcode Districts covering the UK - Districts are often used for sales territory and franchise area applications.

Postcode Sector

A Postcode Sector is everything bar the last two letters of the Postcode (e.g. UB7 0 from UB7.0EB). There are over 9,000 Postcode Sectors covering the UK - Sectors are used for more local and detailed mapping and analysis.

Full Postcode

The Full Postcode is the Postcode as most people would generally know and love it as written on envelopes for addresses. (e.g. UB7 0EB). There are approximately 1.7 million Full Postcodes covering the UK and on average a full postcode is shared by only 15 residential addresses. Locating an address by it's Postcode will generally take you to within 100 metres of the addresses true location and for this reason the full Postcode is often used to map addresses or in navigation systems for logistic applications