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Postcodes - How do they work?

Postcodes have existed in the UK for over 50 years now. It’s hard to imagine how our mail operated before they came to exist. And yet how many of us truly understand what our postcode represents or why it’s there?

When sending mail to a UK address you need to provide a full and accurate address, complete with postcode. The purpose of the postcode is to enable the Royal Mail to sort your post quickly and accurately.


Below is a breakdown of each part of your address:

3X Software Ltd (Addressee Name)
23 Princes Drive (Building number/name and street name)
Colwyn Bay (Postal Town)
Conwy (County)
LL29 8HT (Postcode)


If your property has a name, it is most commonly entered as a standalone line before the street name. For example:

3X Software Ltd Headquarters,

Princes Drive,


Common mistakes include putting your postcode before your county, or melding two separate address categories into one like, like so:

3X Software Ltd,

23 Princes Drive,

Colwyn Bay, Conwy,

LL29 8HT         


The numbers and letters which make up a postcode may seem random at first, but each is significantly vital to tell your street apart from any other. Each section represents your area, district and street in order to make your location easily identifiable via postcode lookup.

Below is a breakdown of each section of a postcode:

LL29 8HT The first 1 or 2 letters represent the postcode area that you live in
LL29 8HT The second part indicates the postcode district that you live in
LL29 8HT The final part of the postcode identifies the unit/Street that you live in


The Royal Mail keeps all its addresses in their Postcode Address File database. 3500 records are updated each day, making it by far the most reliable UK address database system. It holds over 1.8 MILLION postcodes and 29 MILLION residential addresses. For something as complicated as addresses and postcodes (see above), perhaps Postcodes4U could be of help....

If you ever need any further information about postcodes, or want to check addresses against the most reliable address database in the UK, visit We utilize the Royal Mail's Postcode Address File in order to provide the most up-to-date and accurate address information available in the UK. We might also be able to significantly improve your e-commerce business by minimizing lost parcels and improving your customer satisfaction. Visit us and give it a try.