The RM postcode area, also known as the Romford postcode area,[2] is a group of twenty postcode districts in south-east England, within nine post towns.

These cover parts of eastern Greater London and south-west Essex.

In Greater London, the area covers most of the London Borough of Havering (including Romford, Hornchurch, Rainham and Upminster), the eastern part of the London Borough of Barking and Dagenham (including Dagenham itself) and a small part of the London Borough of Redbridge.

In Essex, the area covers most of the Thurrock unitary district (including Grays, Purfleet, South Ockendon and Tilbury), while RM4 covers small parts of the Epping Forest District and the Borough of Brentwood.

The approximate coverage of the postcode districts:[3]