The Schaich springs at about 544 m from the Hengstbrunnen in the forest south of Altdorf a little east of the Gabeleiche at the Rauhen Hau.

From there the river Schaich flows in mainly eastern direction through or at the edge of the areas of the municipalities Altdorf, Holzgerlingen, Weil im Schönbuch, Dettenhausen, Walddorfhäslach, Aichtal and Schlaitdorf.

At the end of its 23.6 km long path with an average bottom gradient of 9.7 ‰ it flows about 228 meters altitude below its source.

[2] At the beginning it runs approximately at the northern edge of the nature area Naturpark Schönbuch and later through its north-eastern part.

Its highest point is the flat, 582.6 m [3] high summit of the Bromberg south of the Hengstbrunnen, over which the southern watershed runs to the large catchment area of the Goldersbach and its tributaries, which drains over the Ammer to the Neckar.