What does a CM11 postcode tell you?

That the address lies in the CM11 district of the CM (Chelmsford) postcode area, which the directory places around Essex. 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.

CM11 postcode district

What the public directories installed here say about the CM11 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	CM (Chelmsford)
live postcodes	453
terminated postcodes	151
streets listed	267
centroid	51.62332, 0.44625
counted on	2026-09-18

Places the directory lists for CM11

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 CM area is reported but not scored.

Essex
Eastern
Basildon
Billericay
Chelmsford
Crays Hill
Ramsden Heath
Ramsden Bellhouse
Downham
Wickford
Brock Hill
Noak Hill

Postcodes in use

453 postcodes in CM11 were in use on the day of the count. A postcode directory says whether a code is in use, never who is there. 151 of its 604 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: 51.62332, 0.44625 — the mean of the live postcodes' centroids, which locates the district, not any building in it.

Streets filed under CM11

OS Open Names files 267 roads under CM11. 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.

A129
Abbots Ride
Allens Road
Anthony Close
Approach Road
Archer Close
Ash Green
Balmoral Close
Barleylands Road
Barns Road
Beams Close
Beams Way
Belvedere Close
Belvedere Lane
Betoyne Close
Beverley Rise
Birds Close
Borwick Lane
Brabner Gardens
Brackendale

the first 20 of 267, alphabetically

Check an address in CM11

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 CM11

curl https://spaw.co/api/v1/address \
  -H "Authorization: Bearer sk_live_…" \
  -H "Content-Type: application/json" \
  -d '{"address": "10 Downing Street, London CM11 …", "country": "GB"}'

Common questions about CM11

What does a CM11 postcode tell you?: That the address lies in the CM11 district of the CM (Chelmsford) postcode area, which the directory places around Essex. 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 CM

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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