In 2001, the village of Oud-Alblas had 1291 inhabitants. The built-up area of the village was 0.19 km², and contained 455 residences. The statistical area "Oud-Alblas", which also can include the peripheral parts of the village, as well as the surrounding countryside, has a population of around 2250.
Oud-Alblas was a separate municipality until 1986, when it became part of Graafstroom. Since 2013 Graafstroom has made part of the new municipality of Molenwaard.