Sheffield is the third - largest English district by population .
The population of the City of Sheffield is 577,800 ( mid-2017 est . ) and it is one of the eight largest regional English cities that make up the Core Cities Group .
City of Sheffield is the third - largest English City of Sheffield by population .
The population of the City of Sheffield is 577,800 ( mid-2017 est . ) and it is one of the eight largest regional English cities that make up the Core Cities Group .