卡尔弗特县（Calvert County, Maryland）是美国马里兰州南部的一个县，西临帕塔克森特河，东临切萨皮克湾。面积894平方公里。根据美国2000年人口普查，共有人口86,474人。县治弗雷德里克王子村 (Prince Frederick)。

成立于1654年。县名纪念马里兰的领主卡尔弗特家族。

Calvert County is a county located in the U.S. state of Maryland. As of the 2010 census, the population was 88,737. Its county seat is Prince Frederick. The county's name is derived from the family name of the Barons of Baltimore, the proprietors of the English Colony of Maryland.