What is a Zip Code UK

Zip code stands for Zone Improvement Plan. Postal codes in the United Kingdom are also called as postcodes. The initial postcode system divided London and other huge cities in the United Kingdom. A full postcode allot an area with a number of addresses or a single major delivery point.

About postal codes in the UK

This UK postcode areas map outline the boundaries of all 5 digit postal code areas in the United Kingdom. This postal code system is developed by the UK national postal service named Royal Mail, to divide the United Kingdom in different specific areas. With this system each UK region gets a distinctive code and locations can be found easily.

Postal code structure of the United Kingdom

This map outline the boundaries of the 5 digit postal codes or districts in the United Kingdom. These 5-digit postal codes contain the following mentioned characteristics and features:

  • The first and second digit shows a specific local town or bigger metropolitan area, like London.
  • The second one or two digits feature a particular region and are followed by a space.
  • The last part of the United Kingdom postal codes consist of one number and two letters. This is called an arbitrary code.

The structure of a postcode is two alphanumeric codes that determines, first the Post Town and second, a small group of addresses in that post town. The first alphanumeric code (the Outward code or Outcode) has either two or four characters and the second (the Inward Code or Incode) always has three characters. The Outcode designate the postcode area and postcode district. It comprises of one or two letters, followed by one digit, two digits or one digit and one letter. This is followed by a space and then the Incode which shows the postcode sector and delivery point (usually a group of around 15 addresses). The incode always has 3 characters, starting with a number (denoting a sector within the district), and ending with two letters (denoting delivery points which are allotted to streets, sides of a street or individual properties). Postcode areas are generally, but not always, named after a major town or city — such as B for Birmingham. A small number are geographic in nature — such as HS for the Outer Hebrides and FY for Fylde.

Each postcode area has a number of post towns which are not themselves alphabetically represented; however each will usually constitute one or more postcode districts. Example: a sizeable part of southern England is covered by the GU postcode area, named after the town of Guildford. Guildford itself consists of postal districts GU1 and GU2. Nearby Working, a major commuter town—6 miles (10 km) away—is a post town within the postal district GU22. The central part of the town or city the postcode area is named after will have the number 1 e.g. B1 (Birmingham), LS1 (Leeds), M1 (Manchester). However, other post towns within the area are then either treated alphabetically—particularly in London—e.g. Chingford on the north-eastern edge of London being E4, whereas adjacent Walthamstow to the south being E17–or geographically— e.g. the Outer Hebrides area HS numbering the districts north to south.

As a general rule, large post towns are numbered from the center outward such that outlying parts have higher numbered districts. However, the disparate post towns within a postal area can be numbered based on various criteria. The town the postal area is named after accepted, this always being 1. In particular, the centrality of a postcode district within a postcode area cannot be reliably inferred from the postcode alone. For instance, SE1 covers a large part of Central London south of the Thames whereas SE2 covers Abbey Wood at the far end of the Elizabeth Line.

Modern postcode system

The Post Office experimented with electromechanical sorting machines in the year 1950s. These devices showed an envelope to an operator, who would press a button designating which bin to sort the letter into. Postcodes were suggested to increase the efficiency of this process by eliminating the need for the sorter to remember the correct sorting for as many places. In January 1959 the Post Office analyzed the results of a survey on public attitudes, towards the use of postal codes, choosing a town in which to experiment with codes. The envisaged format was a six character alphanumeric code with three letters indicating the geographical area and three numbers to identify the individual address. On 28 July Ernest Marples, the Postmaster General, announced that Norwich had been selected, and that each of the 150 thousand private and business addresses would receive a code by October. Norwich had been selected as it already had 8 automatic mail sorting machines in use. The original Norwich format consisted of “NOR,” followed by a space, then a two-digit number (which, unlike the current format, could include a leading zero), and ending with a single letter (instead of the two final letters in the current format).

In October 1965, Tony Benn as Postmaster General announced that postal coding was to be extended to the rest of the country in the next coming years.

On 1 May, 1967 postcodes were introduced in Croydon. The many postcodes for central Croydon began with “CRO”, while those of the surrounding post towns with CR2, CR3 and CR4. The uniform system of a set of three final characters after the space (such as 0AA, known as the inward code) was selected. This was to be the beginning of a ten year plan, costing an estimated 24 dollar million. Within two years it was expected that full coding would be used in Bristol, Aberdeen, Belfast, Brighton, Bromley, Cardiff, Coventry, Manchester, Newcastle upon Tyne, Newport, Reading, Sheffield, Southampton and the Western district of London. By 1967, codes had been introduced to Aberdeen, Southampton, Brighton and Derby. In 1970, codes were introduced to the London Western and North Western postal districts. In December 1970, much Christmas mail was postmarked with the message “Remember to use the Postal Code” although codes were used to sort mail in only a handful of sorting offices.

During 1971, occupants of addresses started to receive notification of their postcode. Asked in the House of Commons about the completion of the coding exercise, the Minister of State for Posts and Telecommunications (whose role superseded that of Postmaster General in 1969), Sir John Eden, stated that it was expected to be completed during 1972. The scheme was finalized in 1974 when Norwich was completely re-coded but the scheme tested in Croydon was adequately close to the final design for it to be retained, with CRO standardized as CR0 (district zero) thus removing the need to create a CR1 district.

A quirk remained: the central Newport (Gwent) area was allocated NPT at a similar time to Croydon becoming CRO, and surrounding areas were (as today) allocated NP1–NP8. NPT lasted until the end of 1984 when it was recoded NP9.

Girobank’s GIR 0AA was the last domestic postcode with a fully alphabetical outward code. That code no longer exists in the Royal Mail’s PAF system, but was taken over by the bank’s current owners, Santander United Kingdom.

Adaptation of earlier systems into national system

When the national postcode system was introduced, many existing postal districts were incorporated into it, so that postcodes in Toxteth (Liverpool 8) start with L8. The districts in both Manchester and Salford gained M postcodes, so Salford 7 became M7 and so on (and similarly in Brighton and Hove, both using the prefix BN). The old coding lives on in a small number of street signs with (for example) “Salford 7” at the bottom end. In other cases, the district numbers were replaced with unrelated numbers. In Glasgow many of its G-prefixed numbers are not used as C1 became G1, W1 became G11, N1 became G21, E1 became G31, S1 became G41, SW1 became G51, and so on. In London (as postally defined), 1917-created postal districts are mapped unchanged to those of today but its much enlarged administrative area, Greater London, was created in April 1965. From that month the remaining 60% of Greater London’s area has postcodes referring to 13 other post towns. Additionally, there were too few postcodes to adequately cover districts in central London (particularly in the WC and EC areas), so these were subdivided with a letter suffix rather than being split into new numbered districts so as to retain the familiar codes.

GB postcodes available as OpenData

Prior to 1 April 2010, the Royal Mail licensed use of the postcode database for a charge of about 4,000 dollar per year. Following a campaign and a government consultation in 2010, the Ordnance Survey released Code-Point Open, detailing each current postcode in Great Britain together with a geo-code for re-use free of charge under an attribution-only licence (Open Government Licence as part of OS OpenData).

Postcodes linked to a variety of UK geographies

The Office for National Statistics (ONS Geography) sustains and publishes a series of freely available, downloadable postcode products that link all current and terminated UK postcodes to a range of administrative, health, statistical and other geographies using the Code-Point Open grid reference.


The postcodes are alphanumeric, and are different in length: ranging from 6 to 8 characters (including a space). Each postcode is characterized into two parts separated by a single space: the outward code and the inward code respectively. The outward code includes the postcode area and the postcode district respectively. The inward code includes the postcode sector and the postcode unit respectively.

:small_blue_diamond: Outward code

The outward code is the part of the postcode before the single space in the center. It is between two and four characters long. Examples of outward codes are “L1”, “W1A”, “RH1”, “RH10” or “SE1P”. A few outward codes are non-geographic, not divulging where mail is to be sent.

:small_blue_diamond: Postcode area

The postcode area is part of the outward code. The postcode area is either one or two characters long and is alphabetical. Examples of postcode areas are “L” for Liverpool, “RH” for Redhill and “EH” for Edinburgh. A postal area may cover a wide area, for example “RH” also covers parts of north Sussex and “BT” (Belfast) covers the whole of Northern Ireland.

:small_blue_diamond: Postcode district

The postcode district is one digit or two digits or a digit followed by a letter.

:small_blue_diamond: Inward code

The inward code is the part of the postcode after the single space in the center. It is 3 characters long. The inward code assists in the delivery of post within a postal district. Examples of inward codes are “0NY”, “7GZ”, “7HF”, or “8JQ”

:small_blue_diamond: Postcode sector

The postcode sector is made up of a single digit (the first character of the inward code).

:small_blue_diamond: Postcode unit

The postcode unit is 2 characters added to the end of the postcode sector. A postcode unit usually represents a street, part of a street, a single address, a group of properties, a single property, a sub-section of the property, an individual organization or (for instance Driver and Vehicle Licensing Agency) a subsection of the organization. The level of discrimination is often based on the amount of mail received by the premises or business. Examples of postcode units are “SW1W 0NY”, “PO16 7GZ”, “GU16 7HF”, and “L1 8JQ”.

Frequently Asked Questions :paintbrush:

How do I find my ZIP code UK?

Royal Mail

Go to Royalmail.com/find-a-postcode, enter your street address, town or city and click Find postcode. Everything is fast and easy! While typing, you’ll get search suggestions. Note that UK zip codes have a special format with outward (postcode area) and inward (postal district) parts, e.g. SW19 3AR.

What means zip code?

Zone Improvement Plan

A ZIP Code is a postal code used by the United States Postal Service (USPS). The term ZIP is an acronym for Zone Improvement Plan; it was chosen to suggest that the mail travels more efficiently and quickly (zipping along) when senders use the code in the postal address.

What is a zip code on a debit card?

Debit Card Zip Code The address that you provided to the bank or credit organization for your account includes the ZIP code of your debit card. For example, if you get mail at 1234 Main Street in Anywhere MN 56799, and that’s the place that the bank has for the account, then the card’s ZIP code is 56789.

Where is zip code on Visa card?

The ZIP code for a Visa credit card is usually just the ZIP code from the cardholder’s current mailing address. ZIP codes are not printed on Visa credit cards, but you can double check a Visa card’s ZIP code by looking at digital and mailed billing statements from the credit card company.


Zip code purposes of identifying a location and routing the mail to that location. A zip code was originally 5 digits long, and now has been expanded to 9 digits for more detailed identification. The 5 digit zip code is still sufficient for sending all items of mail; the 9 digit zip code is used primarily by businesses as they sometimes get a discount for doing so. Zip code stands for Zoning Improvement Plan code.

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