Window U-Factor Calculator
Window U-Factor
Calculate window U-factor for energy efficiency rating.
Formula
U-Factor = Base U - Gas Adjustment - Low-E Adjustment
Frequently Asked Questions
What is a good U-factor for windows?
A U-factor of 0.30 or lower is considered energy efficient.
What is the difference between U-factor and R-value?
U-factor measures heat transfer; R-value is its inverse measuring resistance.