Oberhallau has a population () of 425, of which 2.4% are foreign nationals. Of the foreign population, (), 30% are from Germany, 10% are from Italy, and 60% are from another country. Most of the population () speaks German (97.2%), with Serbo-Croatian being second most common ( 1.0%) and English being third ( 0.5%). The age distribution of the population () is children and teenagers (0–19 years old) make up 22.4% of the population, while adults (20–64 years old) make up 61.6% and seniors (over 64 years old) make up 16%.