Oldsum
| Oldsum Olersem (North Frisian) | |
|---|---|
| The windmill is Oldsum's landmark | |
| Oldsum Olersem (North Frisian) Oldsum Olersem (North Frisian) | |
| Coordinates: 54°44′N 8°27′E / 54.733°N 8.450°E | |
| Country | Germany | 
| State | Schleswig-Holstein | 
| District | Nordfriesland | 
| Municipal assoc. | Föhr-Amrum | 
| Government | |
| • Mayor | Hark Riewerts | 
| Area | |
|  • Total | 13.3 km2 (5.1 sq mi) | 
| Elevation | 4 m (13 ft) | 
| Population  (2023-12-31) | |
|  • Total | 557 | 
| • Density | 42/km2 (110/sq mi) | 
| Time zone | UTC+01:00 (CET) | 
| • Summer (DST) | UTC+02:00 (CEST) | 
| Postal codes | 25938 | 
| Dialling codes | 04683 | 
| Vehicle registration | NF | 
| Website | www.oldsum-auf-foehr.de | 
Oldsum (Fering: Olersem) is a municipality on the island of Föhr, in the district of Nordfriesland, in Schleswig-Holstein, Germany.