The A12 is a major road in Eastern England. It runs north-east/south-west between London and the coastal town of Lowestoft in the north-eastern corner of Suffolk, following a similar route to the Great Eastern Main Line until Ipswich. A section of the road between Lowestoft and Great Yarmouth became part of the A47 in 2017. Between the junctions with the M25 and the A14, the A12 forms part of the unsigned Euroroute E30. Unlike most A roads, this section of the A12, together with the A14 and the A55, has junction numbers as if it were a motorway.

Lowestoft is a coastal town and civil parish in the East Suffolk district of Suffolk, England. As the most easterly UK settlement, it is 110 miles (177 km) north-east of London, 38 miles (61 km) north-east of Ipswich and 22 miles (35 km) south-east of Norwich, and the main town in its district. The estimated population in the built-up area exceeds 70,000. Its development grew with the fishing industry and as a seaside resort with wide sandy beaches. As fishing declined, oil and gas exploitation in the North Sea in the 1960s took over. While these too have declined, Lowestoft is becoming a regional centre of the renewable energy industry.