As of 2015, the average price range for tempered glass windows is between $20 and $45 per square foot. Additional costs vary depending on the type of glass that an individual purchases. For example, additional costs are common for tempered glass that replaces the glass in an existing window fixture.
Tempered glass is a type of glass that is treated with chemicals or heat to increase its strength. Unlike normal glass, tempered glass doesn't shatter into sharp pieces when it breaks. Instead, it breaks into small granules that are less likely to produce sharp edges. While this type of glass can be used in homes, it's often used to make windshields in automobiles.