Chelmsford is the principal settlement of the City of Chelmsford and the county town of Essex, in the East of England. It is located in the London commuter belt, approximately 32 miles northeast of Charing Cross, London, and approximately 22 miles from Colchester. The urban area of the city has a population of approximately 120,000, whilst the district has a population of 168,310.

The main conurbation of Chelmsford incorporates all or part of the former parishes of Broomfield, Great Baddow, Galleywood, Writtle, Moulsham, Widford and Springfield, including Springfield Barnes, now known as Chelmer Village.

The communities of Chelmsford, Massachusetts, Chelmsford, Ontario, and Chelmsford, New Brunswick, are named after the city.

Chelmsford's population consists of a large number of City and Docklands commuters, attracted by the 30–35 minute journey from Central London via the Great Eastern Main Line. The same journey takes approximately 60 minutes by road via the A12.

On 14 March 2012, Lord President of the Privy Council and Deputy Prime Minister Nick Clegg announced that Chelmsford, along with Perth, Scotland and St Asaph, Wales, was to be granted city status. The Letters Patent officially granting city status to Chelmsford from The Queen were received on 6 June 2012.