CM postcode area
The CM area holds 28 districts and 18,674 live postcodes; its largest place is Chelmsford.
| District | Live postcodes | Largest place with its centre there |
|---|---|---|
| CM0 | 564 | Burnham-on-Crouch |
| CM1 | 1,561 | Chelmsford |
| CM2 | 1,314 | West Hanningfield |
| CM3 | 1,588 | Danbury |
| CM4 | 442 | Ingatestone |
| CM5 | 449 | Chipping Ongar |
| CM6 | 989 | Great Dunmow |
| CM7 | 1,349 | Braintree |
| CM8 | 924 | Witham |
| CM9 | 1,072 | Maldon |
| CM11 | 453 | — |
| CM12 | 507 | Billericay |
| CM13 | 702 | Shenfield |
| CM14 | 616 | Brentwood |
| CM15 | 596 | — |
| CM16 | 639 | Epping |
| CM17 | 529 | Old Harlow |
| CM18 | 430 | — |
| CM19 | 394 | Roydon |
| CM20 | 629 | Harlow |
| CM21 | 319 | Sawbridgeworth |
| CM22 | 560 | Takeley |
| CM23 | 1,200 | Bishops Stortford |
| CM24 | 274 | Stansted Mountfitchet |
| CM77 | 462 | Rayne |
| CM92 | 18 | — |
| CM98 | 19 | — |
| CM99 | 75 | — |
Contains OS data © Crown copyright and database right 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Source: Office for National Statistics licensed under the Open Government Licence v3.0. Postcode data is the ONS Postcode Directory, August 2026 edition; counts are live postcodes with a usable location. Northern Ireland postcodes carry a separate licence and are not included; Scotland joins when the site's Scottish coverage does.