The territory's lowest point is at the Lein river near Rodamsdörfle, the highest point is the Grünberg's peak near Unterkochen at 733 metres (2,405 ft).Aalen's territory ranges over all lithostratigraphic groups of the South German Jurassic: Aalen's south and the Flexner massif are on top of the White Jurassic, the town centre is on the Brown Jurassic, and a part of Wasseralfingen is on the Black Jurassic.
Its designated catchment area includes the following municipalities of the central and eastern Ostalbkreis district: Abtsgmünd, Bopfingen, Essingen, Hüttlingen, Kirchheim am Ries, Lauchheim, Neresheim, Oberkochen, Riesbürg and Westhausen, and is interwoven with the catchment area of Nördlingen, situated in Bavaria, 30 kilometres (19 mi) east of Aalen.As Aalen's territory sprawls on escarpments of the Swabian Jura, on the Albuch and the Härtsfeld landscapes, and its elevation has a range of 355 metres (1,165 ft), the climate varies from district to district.Sporting and recreation grounds and parks comprise 1% 152.7 hectares (377 acres), other areas 1.1% 163.9 hectares (405 acres). They are listed clockwise, beginning south, with their respective linear distances to Aalen town centre given in brackets: Oberkochen (6 km or 3.7 mi), Essingen (6 km or 3.7 mi), Heuchlingen (11 km or 6.8 mi), Abtsgmünd (9 km or 5.6 mi), Neuler (10 km or 6.2 mi), Hüttlingen (6 km or 3.7 mi), Rainau (10 km or 6.2 mi), Westhausen (9 km or 5.6 mi), Lauchheim (12 km or 7.5 mi), Bopfingen (20 km or 12 mi) and Neresheim (20 km or 12 mi), all in the Ostalbkreis district, furthermore Heidenheim an der Brenz (18 km or 11 mi) and Königsbronn (10 km or 6.2 mi), both in Heidenheim district.Aalen's territory consists of the town centre (Kernstadt) and the municipalities merged from between 1938 (Unterrombach) and 1975 (Wasseralfingen, see mergings section).The Aal is a small river located only within the town's territory.
Next, the Kocher crosses the district of Wasseralfingen, then leaves the town for Hüttlingen.They are at last followed by the Trossingen Formation already belonging to the Late Triassic.Until 1939 iron ore was mined on the Braunenberg hill. The maximum extent of the town's territory amounts to 18 kilometres (11 mi) in a north-south dimension and 25 kilometres (16 mi) in an east-west dimension.Rivers originating near Aalen are the Rems (near Essingen, west of Aalen) and the Jagst (near Unterschneidheim, east of Aalen), both being tributaries of the Neckar, just like the Kocher.The elevation in the centre of the market square is 430 metres (1,410 ft) relative to Normalhöhennull.The south-west is part of the Albuch, the east is part of the Härtsfeld, these two both being parts of the Swabian Jura.