CM99 postcode district: Chelmsford and around, Essex
CM99 is a postcode district in Essex, with 75 postcodes in use in 1 sector. It has postcodes in Chelmsford. Its council is Chelmsford.
- Postcodes in use
- 75
- Sectors
- 1
- Council
- Chelmsford
- Places
- Chelmsford
Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026. See all our data sources
Every postcode in CM99, and which are new since 2020
- New since 2020: 23
- In use before 2020: 52
- Outline: where 5 or more new postcodes since 2020 lie together
Of the 75 postcodes in CM99 that ONS places, 23 are new since 2020 and 52 were in use before 2020.
Each mark is a postcode's centre point as ONS gives it, not a building. Press one to see its postcode and open its page. New since 2020 means it came into use in January 2020 or later. A dashed outline shows where 5 or more lie within 200 metres of each other. It is not a boundary, and no boundary is drawn. Where marks overlap, the one first in the key is drawn; the counts include every postcode. Names in italics are council wards: we hold no town or village names here.
The middle of its postcodes: latitude 51.7425, longitude 0.5006. Open this area on OpenStreetMap
Source: Office for National Statistics (ONS) Postcode Directory, August 2026, loaded 20 October 2026, the centre point of each postcode; when each came into use: the same directory; roads, rivers and built-up areas: Contains OS data © Crown copyright and database right 2026. Drawn by us. Street map: Ordnance Survey, OS Open Zoomstack, Open Government Licence v3.0, drawn with MapLibre. How we use them
The 5 newest postcodes
Where the new postcodes lie together
- 23 new postcodes since 2020, outlined on the map. CM99 2AF, is the newest of them.
Is CM99 at risk of flooding?
None of the 75 postcodes in CM99 is on the Environment Agency's list of postcodes with a home or business in an area at risk of flooding from rivers or the sea.
Homes and businesses in an area at risk of flooding from rivers or the sea, as the Environment Agency counts them, added up over the postcodes. It is for the land, not each building, and leaves out surface water, groundwater and sewers. Each postcode page has its own figures and its flood warning areas.
Source: Environment Agency, Risk of Flooding from Rivers and Sea (postcodes in areas at risk), published 6 July 2026, Open Government Licence v3.0. How we use it
Postcodes in CM99
Pick a sector, then a postcode. A sector is the district plus the next digit.
UK postcode format explainedPlaces in CM99
Towns and villages with postcodes in CM99, and how many each has here.
Who covers CM99
How many of the district's postcodes in use fall under each council, constituency and police force area.
Next to CM99
"Next to" is by number: the district before CM99 in the CM area.
Check a postcode
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