Laconia is a city in Belknap County, New Hampshire, United States. The population was 16,871 at the 2020 census, up from 15,951 at the 2010 census. It is the county seat of Belknap County. Laconia, situated between Lake Winnipesaukee and Lake Winnisquam, includes the villages of Lakeport and Weirs Beach. Each June, the city hosts Laconia Motorcycle Week, also known as "Bike Week," one of the country's largest motorcycle rallies.