Sleaford is a market town and civil parish in the North Kesteven district of Lincolnshire, England. On the edge of the Fenlands, it is 11 miles north-east of Grantham, 16 mi west of Boston, and 17 mi south of Lincoln. It is the largest settlement in North Kesteven with a population of 19,807 in 2021. Centred on the former parish of New Sleaford, the modern boundaries and urban area include Quarrington to the south-west, Holdingham to the north-west and Old Sleaford to the east.