Check any UK postcode

The UK postcode system was introduced by Royal Mail in the 1960s and rolled out nationwide by 1974. Each postcode identifies a precise delivery point, making it one of the most granular address reference systems in the world. There are roughly 1.79 million active postcodes covering around 31 million delivery addresses, though the number of addresses per postcode varies greatly: a single large office building may have its own code, while a sparsely populated rural area may share one across several miles of countryside.

Every postcode is made up of two parts separated by a space. The outward code, the part before the space, directs mail to the correct postal district. The inward code, the part after the space, narrows delivery to a specific street or cluster of properties. Together they form a short, machine-readable reference used far beyond postal delivery, from GPS navigation to electoral registration to emergency response planning.

Entering a postcode here returns considerably more than a map pin. Each result includes the post town and address area, the local authority and electoral ward, the parliamentary constituency, the NHS region, and the nation (England, Scotland, Wales or Northern Ireland). You also get precise latitude and longitude coordinates and a ranked list of nearby postcodes sorted by distance.

The underlying data comes from the National Statistics Postcode Lookup compiled by the Office for National Statistics. It is updated every quarter to reflect new housing developments, boundary reviews and postcodes that have been retired or reassigned.

Postcodes follow a four-level hierarchy. At the top is the postcode area, identified by one or two letters: SW for south-west London, LS for Leeds, EX for Exeter. There are 124 areas across Great Britain. Each area is divided into districts by adding a number after the letters, giving codes like SW1, LS2 and EX4. The roughly 3,000 postcode districts are the unit most widely used in logistics, retail catchment analysis and direct marketing.

Districts are subdivided into sectors, identified by the digit immediately following the inward code space, and finally into individual unit postcodes. In the postcode W1A 1AA, for example, W is the area, W1A is the district, W1A 1 is the sector, and W1A 1AA is the full unit postcode. Our district pages list every active postcode within a district alongside population figures, nearby districts and a full breakdown of coverage.

Postcode boundaries reflect Royal Mail delivery workload rather than geographic size. A postcode in central London or Manchester might cover a single office block or a short row of terraces because address density is high and sorting efficiency demands smaller zones. The equivalent postcode in rural Northumberland or the Scottish Borders may span several square miles because a single delivery round covers scattered farms, hamlets and isolated properties across open countryside.

Royal Mail reviews postcodes continuously. New housing estates, regeneration schemes and commercial developments prompt the creation of new postcodes, while demolition and urban change retire old ones. Around 3,000 postcodes are added, amended or terminated each year, which is why postcode databases need regular updating to stay accurate.

Each individual unit postcode is assigned to exactly one local authority and one parliamentary constituency in the ONS dataset. However, postcode districts and areas frequently straddle several councils and multiple constituencies, so looking up the district alone is not a reliable guide to administrative responsibility.

This matters for practical decisions. Council tax billing, planning permission, waste collection schedules and school admission policies are all administered at local authority level. Properties sitting close to a council boundary can belong to different authorities even when they are on the same street. Checking the specific unit postcode rather than the broader district gives you the authoritative assignment, which is what this tool provides.

Yes. Royal Mail assigns a dedicated postcode to any address that generates sufficient mail to warrant one. Large hospitals, universities, government departments, major retailers and prominent office complexes often have unique postcodes that cover a single building or campus. These are classified as large user postcodes and represent a small but significant share of the total.

At the other end of the scale, remote properties may share a postcode with only two or three neighbours on a long rural delivery round. The system is entirely driven by sorting and delivery need rather than by any principle of equal geographic coverage.

A small number of postcodes are not linked to any physical location. They are used for PO boxes, freepost addresses, business reply services and certain mail-order operations. They appear in the postcode database but cannot be plotted on a map. Our checker flags these where the ONS data allows, so you will not be left with a blank or misleading map result when looking one up.

A postcode is a delivery reference, not a legal boundary, and several important distinctions follow from that. First, postcodes change regularly, so a code that was valid two years ago may have been split, merged or retired since. Databases that are not updated quarterly carry stale records that can cause address matching failures.

Second, school catchment areas are set independently by local authorities and do not follow postcode boundaries. Being within a particular postcode does not guarantee admission to a nearby school; councils publish their own catchment maps and those should always be consulted directly for admissions purposes.

Third, properties close to a local authority boundary can be deceptive. Two houses on opposite sides of the same street sometimes fall in different councils, different constituencies or, in border areas, different countries. The only reliable check is at the individual unit postcode level, which is exactly what this tool provides.

The first experimental postcode was trialled in Norwich in 1959, using an alphanumeric format designed to work with early automated sorting machinery. The concept was refined through the 1960s and a phased national rollout began in Croydon in 1967. By 1974 the system covered the entire UK. The format has remained broadly consistent ever since, though the dataset expands by hundreds of new postcodes each year as the country grows and changes.

What began as a tool for mechanical letter sorting is now the backbone of services across dozens of sectors. Satellite navigation, property valuation, broadband coverage mapping, emergency dispatch, electoral management and retail site selection all depend on postcode data. Royal Mail licenses the dataset commercially, while the ONS publishes a free version linked to administrative geographies, which is the source used by this site.