The CM postcode area, also known as the Chelmsford postcode area, is a group of 25 postcode districts in England, which are subdivisions of 16 post towns. These postcode districts cover central Essex (including Chelmsford, Harlow, Brentwood, Billericay, Braintree, Burnham-on-Crouch, Dunmow, Epping, Ingatestone, Maldon, Ongar, Southminster, Stansted and Witham), plus a small part of east Hertfordshire (including Bishop's Stortford and Sawbridgeworth) and a very small part of the London Borough of Havering.