The Kahl is a river in the northern Spessart in Bavaria and Hesse, Germany. It is a right tributary of the Main and is 35.6 km (22.1 mi) long. The name Kahl comes from the Old High German word kaldaha, which means cool and clear. The Kahl rises from two sources left and right of the road at the foot of the Spessart hills, near Kleinkahl. These springs produce 50–60 litres per second. The Kahl flows into the river Main in Kahl am Main. The mouth is near the old Kahl Nuclear Power Plant. The largest tributaries are Westerbach, Sommerkahl, Reichenbach and Geiselbach.

Tributaries from source to mouth:

• 
  The right spring of the Kahl
• 
  The left spring
• 
  Mouth in the river Main

• List of rivers of Bavaria
• List of rivers of Hesse