What does a PO1 postcode tell you?

That the address lies in the PO1 district of the PO (Portsmouth) postcode area, which the directory places around Portsmouth. The inward half of the full postcode narrows it to a street or a building; the district alone does not, and an address written with a district and no inward half cannot be checked against the register.

Does a street listed here mean an address on it exists?

It means OS Open Names lists a road of that name under the district, which is what the address lookup answers as a street-level match. It says nothing about any building on it: Great Britain publishes no open register of buildings, so the lookup answers exists: null there and confirms the street alone.

Who lives at these postcodes?

Nobody on this page. A postcode directory says whether a code is in use, never who is there, and a streets register lists roads, not occupants. The address lookup carries no field about a person and never will.

PO1 postcode district

What the public directories installed here say about the PO1 postcode district: how many of its postcodes are in use, the places OS Open Names lists for them, the streets it files under the district and the district's centroid. Counted from the national postcode directory and OS Open Names on 2026-09-18, and never about who is at an address.

postcode area	PO (Portsmouth)
live postcodes	911
terminated postcodes	744
streets listed	352
centroid	50.79946, -1.08966
counted on	2026-09-18

Places the directory lists for PO1

OS Open Names places the district's postcodes in these settlements, boroughs, counties and regions, most often first. A town written as any of them matches the directory in an address lookup, and one written as another place in the PO area is reported but not scored.

Portsmouth
City of Portsmouth
South East

Postcodes in use

911 postcodes in PO1 were in use on the day of the count. A postcode directory says whether a code is in use, never who is there. 744 of its 1,655 postcodes have been terminated: a real address written with one has moved on, which is not the same thing as a typo, and the address lookup scores it rather than refusing it.

Centroid: 50.79946, -1.08966 — the mean of the live postcodes' centroids, which locates the district, not any building in it.

Streets filed under PO1

OS Open Names files 352 roads under PO1. A road is filed under one district even where it runs through several, so a street missing here may be listed under a neighbouring district — which is why the address lookup never calls a British street absent.

Adames Road
Admiral's Walk
Admiralty Road
Aldrich Road
Alec Rose Lane
Alexandra Road
Alfred Road
All Saint's Road
All Saints' Street
All Saints Road
Alver Road
Anchor Gate Road
Anchor Lane
Andrew Bell Street
Anglesea Road
April Square
Ariel Road
Armory Lane
Arundel Street
Australia Close

the first 20 of 352, alphabetically

Check an address in PO1

The address checker opens on Great Britain with the district in the field: add the street, the number and the full postcode, and it answers the postcode's status, whether the street is filed under the district, and what kind of delivery point the address names.

Check an address in PO1

curl https://spaw.co/api/v1/address \
  -H "Authorization: Bearer sk_live_…" \
  -H "Content-Type: application/json" \
  -d '{"address": "10 Downing Street, London PO1 …", "country": "GB"}'

Common questions about PO1

What does a PO1 postcode tell you?: That the address lies in the PO1 district of the PO (Portsmouth) postcode area, which the directory places around Portsmouth. The inward half of the full postcode narrows it to a street or a building; the district alone does not, and an address written with a district and no inward half cannot be checked against the register.
Does a street listed here mean an address on it exists?: It means OS Open Names lists a road of that name under the district, which is what the address lookup answers as a street-level match. It says nothing about any building on it: Great Britain publishes no open register of buildings, so the lookup answers exists: null there and confirms the street alone.
Who lives at these postcodes?: Nobody on this page. A postcode directory says whether a code is in use, never who is there, and a streets register lists roads, not occupants. The address lookup carries no field about a person and never will.

Where the counts come from

ons-postcode-directory · version 2026-08 · Contains ONS, OS and Royal Mail data © Crown copyright and database right 2026, Open Government Licence v3.0. Northern Ireland postcodes are excluded: their reuse needs a Land & Property Services licence.

Data synced on 2026-09-18: the newest register or postcode directory copy installed here.

Other districts in PO

Wrong result, or is it about you? If this tool said something you think is wrong, tell us and a person reads it. If Spaw is holding data about you and you never signed up here — a customer may have had your address verified, or reported that a message to it bounced — erase it yourself, confirmed by mail to that address and with no account needed.

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