# Postcode

A postcode is the code a postal service uses to sort mail to a delivery area, called a ZIP code in the United States, an Eircode in Ireland and a PIN in India.

Date: 2026-09-10

A postcode is the code a postal service uses to sort mail to a delivery area. It is called a ZIP code in the United States, an Eircode in Ireland, a PIN in India, and `postal_code_type` says which of those a country uses.

## What Spaw answers

Four fields, and they answer different questions. `postal_code_valid` says whether the code matches the country's own pattern. `postcode_status` says what the national postcode directory records — `live`, `terminated`, or null where no directory is installed. `locality_matches_postcode` says whether the town given agrees with the directory. Two reasons come out of this: [`invalid_postal_code`](/docs/reasons/invalid_postal_code) for a code that cannot be one, and [`postcode_not_found`](/docs/reasons/postcode_not_found) for a well-formed code that a complete directory does not list.

A terminated postcode is a real address whose code was retired, not a typo. It scores +30 and is reported rather than refused.

## Coverage, stated plainly

One directory is installed: Great Britain's. Northern Ireland's BT postcodes are excluded from it, so they answer as though no directory existed. It publishes no post town, which is why `locality_matches_postcode` stays null for British addresses.

A postcode is also not an address. A UK code is a routing unit covering a group of delivery points — one side of a street, one office block — and turning a code into the addresses inside it needs a licence this service does not hold, so that endpoint answers `501 ADDRESS_LIST_UNAVAILABLE` rather than guessing.

Reference: https://spaw.co/glossary/postcode