Postcodes
What Is a Postcode? How Postal Codes Work
A postcode is a short code added to an address to help sort and deliver mail. Learn how postal codes work and how a UPCS code differs.
Updated 14 October 2026 · 3 min read
A postcode is a short sequence of letters, numbers, or both that is added to a postal address. Its original job is practical: it lets postal services sort mail quickly and send it to the right area without reading the whole address.
Postcode, postal code, ZIP code and PIN code
The same idea goes by different names depending on where you are:
- Postcode is the common term in the United Kingdom and Australia.
- Postal code is the general international term, and the one used in Canada.
- ZIP code is the name used in the United States.
- PIN code is the name used in India.
What a postcode actually identifies
A postcode normally identifies an area or a group of addresses, not one exact point. In one country it might narrow things down to a single street or a few buildings; in another it might cover a whole district. That is enough for sorting mail, but it often cannot tell a driver exactly where a gate, entrance, or house is.
Formats vary by country
There is no single worldwide format. Some countries use only digits, others mix letters and numbers, and the length differs. For example:
| Country | Typical format |
|---|---|
| United States | Five digits (optionally followed by four more) |
| United Kingdom | Letters and numbers, such as SW1A 1AA |
| Canada | Alternating letters and digits, such as K1A 0B1 |
| Pakistan | Five digits |
Always check the postal authority of the country you are sending to for the exact rules.
How a UPCS code is different
A UPCS code does a different job from a postcode. Instead of describing an area for mail sorting, it is generated from the exact coordinates you pick on the map, so it points to one specific place. A UPCS code looks like PK-XXXX-XXXX: a two-letter country prefix followed by two blocks of characters.
UPCS codes are not official postal codes and do not replace them. They are most useful as a precise addition to an address, for example to help a courier find an entrance that a street address does not describe well.
Where to go next
If you want to try it, the help centre walks through generating a code. For how postal codes work in a specific country, see our Pakistan guide.
Frequently asked questions
Is a postcode the same as a ZIP code?
A ZIP code is the name the United States uses for its postal code. "Postcode" and "postal code" are the general terms used elsewhere, so they describe the same idea under different names.
Does every country have postcodes?
No. Most countries do, but a few places have historically operated without a nationwide postcode system. Where one exists, its format and coverage are set by that country's postal authority.
Is a UPCS code an official postcode?
No. A UPCS code is not issued by any government or postal authority and does not replace an official postcode. It identifies a specific point you choose on the map, and can be shared alongside a normal address.