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What are postal codes and how to find them

Postal codes were developed to assist in the delivery of post in increasingly complex city environments. Starting with a basic subdivision of London in 1857 and gradually adopted by other major cities across Europe. Nowadays, we use a new and improved postal code system which enables us to deliver various types of goods and communications to specific individuals in an efficient manner. Here, we discuss postal codes in detail and how to find them, to utilise as part of your business operations. 

What are postal codes? 

Postal codes are unique across the world, much like a telephone number. You probably know your postal code like the back of your hand, but you probably don’t know the postcode of someone from a twinned city in Switzerland. From the UK to the USA and Australia, we’ve explored the difference in postal codes across the world, how to find them and their history. 

Where did the postcode come from?

In the UK, Norwich was the first city to adopt a modern postcode system in 1959. These were particularly prominent in London, in the mid-20th century the city was divided into ten postal districts – N, NW, NE, S, SW, SE and E.

When it came to testing the system, the intended format was a six-character alphanumeric code consisting of three letters marking the geographical area and three numbers identifying the particular address.

How postal codes are different in each country

Each country has its own system to determine its postal system. There’s a lot of factors that come into play with this technical system.

United Kingdom

The postcode in the UK was first introduced in Norwich (1959), using the letters NOR. By October 1965, it was confirmed that the postal system was to be extended throughout the rest of the county. The new formula consisted of the first three letters of a city, then followed by a number.

This was rolled out originally in Croydon, using CRO – surrounding towns would get the code CR2, CR3, and CR4. This was then implemented in major UK cities over the next two years.

United States

Locally known as a ZIP code, postal codes were introduced in the States in 1963. Known as the ZIP + 4 Code, in 1983, the United States Postal Service expanded the ZIP Code system to include four more digits. The additional digits identify even more precisely the destination.


Unlike the UK, Germany’s postal system is totally numerical. Introduced in 1941, area codes in Germany consist of 2-5 digits. Shorter area codes are typically used for larger cities, while lengthier area codes are used for smaller communities.


First introduced in 1964, the French introduced an automated sorting system that was around for eight years, until they rolled out the 5-digit numerical system which is familiar today. Counties in France are divided into administrative subdivisions known as départements. Each subdivision has a unique postal code, which is represented by the first two numbers.


Before the introduction of postal codes, there required a three-step process including skilled mail sorters before any mail arrived at its intended destination. So, you can imagine, the introduction of a postal code system was a breakthrough for some 8,000 delivery offices in Australia – which was introduced in 1967.


First implemented in Montreal in 1944, other cities in Canada took a while to catch on to the postal code revolution. The early 1960’s saw other cities being divided into postal zones. In Canada, the postal code is a six-character uniformly organised, alphanumeric code.


Unlike any other country mentioned in this list, Ireland has only recently launched a national postal code system. Known as Eircode, this system was introduced in 2014 and makes Ireland, to this day, the only country in the world that has a unique postal code for each individual address.

How would you validate a postal address?

Businesses need to be able to determine and validate a postal address in order to get their products, or services, to partnering businesses, clients and customers. Raw address data must be checked and validated against a government address database, such as the UPS database, before it may be used.

Products like Address Auto Complete and Postcode Lookup give users peace of mind, by validating the postcode and making sure its correct, using Royal Mail PAF Data. With Fetchify’s reliable and accurate address validation system, you can rest assured your consumers will speed through checkout and receive their orders to the right addresses, encouraging more conversions and customer loyalty as well as combatting failed deliveries.

Please note: Post code Lookup is for UK based customers only, whereas Address Auto-Complete can be used globally.

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About Fetchify

We are a pioneer in SaaS address lookup and data validation solutions. We process millions of data transactions each day for thousands of clients ranging from small e-commerce startups to large household brands such as Heinz and RBS. Our flagship products Address Auto Complete and Postcode Lookup reduce friction on checkouts, leading to increases in conversion rate of up to 40%, and helps reduce failed deliveries by as much as 75%. Since launching in 2008, we have differentiated by our ease of integration and exceptional support. We provide a full suite of data validation solutions including Phone Validation, Email Validation, UK Bank Validation, and Data Cleansing.