Coulsdon (/ˈkuːlzdən/, traditionally pronounced /ˈkoʊlzdən/) is a district of south London, mainly within the London Borough of Croydon, with parts of Coulsdon also falling under the London Borough of Sutton and Reigate & Banstead. It is south of Croydon's historic boundaries at Purley and is approximately 13 miles (20.9 km) from Charing Cross.