Postal Code BT21 – Donaghadee, Northern Ireland

Postal Code BT21 for Donaghadee, Northern Ireland is part of the United Kingdom postal code system, which uses an alphanumeric code of 5-7 characters (e.g. EC1A 1HQ). Addresses here are organised as Post Town → Locality → County. Within the code structure it maps to Postcode Area BT and Postcode Unit BT21.

Administratively it is recorded in Northern Ireland within United Kingdom. Postal codes are assigned by delivery route rather than by administrative boundary, so a single code can cover more than one locality and a locality can fall under several codes.

No building-level records are held for this code in the imported dataset, so only the code and its location details are shown. The absence of records does not mean the postal code is unused.

Couriers, e-commerce checkout forms and address autocomplete tools all rely on the postal code to route mail and to check that a stated address matches the code. Because a postal code identifies a delivery area rather than a single building, two addresses that share the same code can still be some distance apart.

Always write United Kingdom Postal Code in full when completing a form, including any leading zero. Enter a valid UK postcode, e.g. EC1A 1HQ. Data source: a third-party open dataset. This is a reference snapshot, not a live government feed, so confirm the code with the sender, carrier or postal authority before relying on it.