The postal counties of the United Kingdom are subdivisions of the UK sometimes used in addressing posted items and which do not correspond exactly to traditional or administrative boundaries. The Royal Mail still uses them internally but no longer requires a county on any item of mail, preferring the use of correct post town and postcodes. However, counties of one sort or another are still routinely included in addresses.

Traditionally, a British postal address required a (postal) county to be listed, though since 1996 the Royal Mail has indicated that it no longer requires this and will accept both the traditional and administrative counties; in fact the addresses generated by the "Address Finder" on the Royal Mail website do not include counties at all, even for post towns such as "Newport" (which could be Newport, Monmouthshire or Newport, Isle of Wight and is also the name of a number of smaller communities which are not post towns). However from an organisational point of view they still follow their own 'postal counties', whilst many individuals and organisations still list a county in their address, and a lot of forms include a section for county. It is, in fact, the postal counties rather than the administrative counties (which are the ones displayed on maps) or traditional counties which people normally use as their reference.

In non-metropolitan areas in England, the postal counties broadly follow the post-1974 administrative counties but there are many places where there are differences, such as Denham which is in both the traditional and administrative county of Buckinghamshire but postally is in Middlesex. In 1996, some unpopular administrative counties such as Avon and Humberside were abolished and common usage now divides Avon (in postal terms) between Somerset, Gloucestershire and Bristol, and Humberside between East Yorkshire and Lincolnshire - following the the traditional county boundaries (though 'Avon' and 'Humberside' both remain postal counties).

The 1974 administrative changes were also followed with regard to metropolitan areas, so Sunderland was referred to as 'Sunderland, Tyne and Wear' not 'Sunderland, Co. Durham'. However in deference to local sentiment the Greater Manchester area continued (and continues) to be split, in postal terms, between Lancashire and Cheshire. Other small exceptions apply in peripheral areas of metropolitan counties (using the traditional county in defiance of the official postal county) e.g. Coventry is often referred to as being in Warwickshire, not the West Midlands, and Southport in Lancashire (not Merseyside).

The London postal district is especially confusing because it does not conform to the boundaries of either the London County Council or the Greater London Council/Greater London Authority whilst other parts of the Greater London administrative area are in the postal counties of variously Surrey, Kent, Essex and Middlesex.

In Wales, the new 1974 administrative counties were adopted by the Post Office, so that Rhuddlan was no longer postally in Denbighshire, but in Clwyd. In Scotland however the traditional counties were retained by the Post Office. Thus Alva, despite being in the Central administrative region after 1974, was still postally in Clackmannanshire. In both Scotland and Wales local government was reorganised in 1996, so that in some places administrative counties reverted to traditional counties once more (e.g. Pembrokeshire, Angus) but in others the post-1974 administrative areas were retained (e.g. Powys, Highland). Thus postal confusion reigns throughout the country and usage differs widely from person to person.

See also

• Post town