What Is a UPRN? The Complete Guide to UK Property Reference Numbers

What is a UPRN?

A Unique Property Reference Number (UPRN) is a unique numeric identifier assigned to every addressable location in Great Britain. Think of it as a postcode — but for individual properties instead of streets.

Every house, flat, commercial unit, and even some land parcels has its own UPRN. There are approximately 29 million UPRNs in the UK, maintained by local authorities and coordinated by the GeoPlace partnership between Ordnance Survey and the Local Government Association.

What does a UPRN look like?

A UPRN is simply a number — typically 8 to 12 digits, with no letters, spaces, or special characters:

100022612238
10090067699
200003553960

The number itself doesn't encode any geographical information. It's an opaque identifier — a random-looking integer that maps to exactly one physical address.

Why do UPRNs matter for developers?

If you're building anything that touches UK property data, the UPRN is your primary key. Here's why:

• Postcodes are ambiguous. SW1A 1AA covers multiple addresses. A UPRN points to exactly one.
• Addresses change. Streets get renamed, buildings get subdivided, flats get renumbered. The UPRN stays constant across all of these changes.
• Cross-referencing. EPC data, Land Registry records, council tax bands, planning applications — all of these can be linked via UPRN. It's the join key across UK property datasets.
• Deduplication. "Flat 1, 10 High St" and "1, 10 High Street" and "First Floor Flat, 10 High Street" might all be the same property. The UPRN resolves this instantly.

How to look up a UPRN

There are several ways to find the UPRN for a specific property:

1. Postcode lookup via API

The fastest programmatic approach. Send a postcode and get back all addresses with their UPRNs:

curl "https://homedata.co.uk/api/address/postcode/SW1A1AA/" \
  -H "Authorization: Api-Key YOUR_API_KEY"

Response:

{
  "postcode": "SW1A 1AA",
  "count": 4,
  "addresses": [
    {
      "uprn": 100023336956,
      "address": "10, DOWNING STREET, LONDON, SW1A 1AA",
      "building_number": "10",
      "building_name": "",
      "sub_building": "",
      "street": "DOWNING STREET",
      "town": "LONDON"
    },
    ...
  ]
}

2. Address search

If you have a partial address, search for it and the API returns matching addresses with UPRNs:

curl "https://homedata.co.uk/api/address/find/?q=10+downing+street" \
  -H "Authorization: Api-Key YOUR_API_KEY"

3. Find your own UPRN

Several councils publish UPRN lookups online. You can also find your UPRN on your council tax bill or via the Find My Address tool.

What data can you get from a UPRN?

Once you have a UPRN, you can pull a rich set of property data. Here's what's available through the Homedata API:

UPRN vs USRN vs TOID

The UK has several geographic reference numbers. Here's how they differ:

• UPRN — Unique Property Reference Number. Identifies an addressable location (building, flat, property).
• USRN — Unique Street Reference Number. Identifies a street or road segment.
• TOID — Topographic Identifier. Ordnance Survey's ID for any map feature (buildings, roads, land parcels, water).

For property data applications, the UPRN is almost always what you need. USRNs are useful for highways and infrastructure work. TOIDs are primarily used in GIS and mapping contexts.

Common UPRN pitfalls

• Don't store UPRNs as integers everywhere. While they're numeric, some systems truncate large numbers. Store as a string or bigint to be safe.
• New builds may not have UPRNs yet. There's typically a lag between a property being built and its UPRN being assigned by the local authority.
• One address can have multiple UPRNs. If a building is subdivided into flats, each flat gets its own UPRN, and the building itself may retain one too.
• UPRNs don't cover Northern Ireland. The system is Great Britain only. Northern Ireland uses Pointer addresses (maintained by Land & Property Services).

Getting started

Ready to build with UPRNs? Get a free API key — no credit card required:

1. Create a free Homedata account (takes 30 seconds)
2. Grab your API key from the developer dashboard
3. Make your first UPRN lookup: GET /api/address/postcode/{postcode}/

The free tier gives you 100 API calls per month — enough to prototype and test. See our Getting Started guide for a full walkthrough, or jump straight to the API Reference.