The elevation of the territory is 351 to 498 m. The area of the district is 378 hectares.

The territories of the following villages adjoin to Obernau, they are called clockwise beginning in the north: Nellingsheim, Bad Niedernau, Schwalldorf and Bieringen.

Obernau has a population of 503 people (31/01/08) and is therefore the second smallest district of Rottenburg.

At an area of 3.78 km² (2.2 sq mi) this corresponds to a population density of 133 people per km², or 345 per sq mi.

The population of the village is predominantly Roman Catholic.