Using Automatic Solve

Specifies whether SOLIDWORKS should automatically do the computation to solve the sketch geometry of your part as you create it.

To turn automatic computation on or off:

Click Tools > Sketch Settings > Automatic Solve. A check mark next to the menu item means that computations are solved automatically.
When Automatic Solve is off, a message in the status bar says Auto-Solve Mode Off.
When you are in the process of changing many dimensions in an active sketch, you may want to turn off the Automatic Solve option temporarily.