PAF vs open data: what UK address coverage actually looks like
How Royal Mail's PAF compares with OS Code-Point Open and OpenStreetMap for UK address coverage — with dated figures and sources for each dataset.
# PAF vs open data: what UK address coverage actually looks like
Royal Mail's Postcode Address File (PAF) is the only UK address dataset that carries individual delivery points — over 29 million of them, plus 1.8 million postcodes. The main open datasets stop short: OS Code-Point Open covers postcodes but not premises, and OpenStreetMap's address data is crowdsourced with no completeness guarantee. If you are choosing an address validation API, the difference matters: open data can tell you roughly where a postcode is; PAF can tell you whether a specific building exists.
What each dataset is
Royal Mail PAF is the proprietary database of UK postal delivery points. Royal Mail is required to maintain it under section 116 of the Postal Services Act 2000, and its charges are regulated by Ofcom. As of the Wikipedia article fetched on 3 October 2026, PAF contains over 29 million postal addresses and 1.8 million postcodes. It is the dataset Royal Mail's own operations run on, and the one licensed address APIs sync from.
OS Code-Point Open is Ordnance Survey's open dataset of postcode locations for Great Britain. Per Ordnance Survey's product page (fetched 3 October 2026), it contains 1.7 million postcodes, is updated every three months, and is free to use. Crucially, it maps each postcode to a single geographic point — it does not contain individual delivery points or premises names. The address-level equivalent, OS GB Address, is a paid product.
OpenStreetMap collects UK addresses through volunteer contributions using the addr:housenumber and related tags, under the ODbL licence. Coverage varies sharply by area and there is no completeness guarantee: OSM makes no claim to contain every address, and we could not obtain a verified UK-wide addr:housenumber count at time of writing (see "What we could not verify" below).
Coverage comparison
| Dataset | Coverage | What you get | Update cadence | Licence | Source (fetched 3 Oct 2026) |
|---|---|---|---|---|---|
| Royal Mail PAF | Over 29 million postal addresses, 1.8 million postcodes | Individual delivery points, premises names, delivery-point status | Continuous (Royal Mail operations) | Proprietary, licensed | Wikipedia, Postcode Address File |
| OS Code-Point Open | 1.7 million postcodes in Great Britain | One geographic point per postcode; no individual premises | Every three months | Open, free to use | ordnancesurvey.co.uk/products/code-point-open |
| OpenStreetMap UK | Not quantified — no verifiable UK-wide count available | Crowdsourced building addresses where tagged; varies by area | Continuous (volunteer edits) | ODbL | OSM wiki, tagging documentation |
What this means when choosing an API
- Postcode-level lookups can run on open data: Code-Point Open gives you a location for any GB postcode at no cost.
- Address-level validation — does this flat exist, is the premises name right, is this address deliverable — requires PAF or an equivalent licensed dataset. No open dataset substitutes for it.
- Crowdsourced data can be useful as a supplement but should not be treated as a coverage baseline, because nothing asserts its completeness.
Postio is a direct Royal Mail PAF licensee with full UK PAF coverage — 30M addresses, synced nightly with Royal Mail — available pay as you go, with 100 free lookups on sign-up. See pricing.
What we could not verify
We tried to quantify OpenStreetMap's UK address coverage and could not. The ohsome API rejected our queries (parameter error, then a data-window error, then a timeout), and taginfo's UK endpoints did not return counts. Rather than publish an unsourced number, we have left the OSM row qualitative. If you have a checkable UK addr:housenumber count, we will update the table with the source.
We also note that Royal Mail's own PAF pages were not fetchable when we researched this piece (the site blocked automated access), so the PAF figures above are cited via Wikipedia's PAF article as fetched on 3 October 2026 rather than from Royal Mail directly.
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