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U-Factor Heat-Loss Comparison

Compare the relative conductive heat-loss reduction between your current window U-factor and a new window U-factor.

Screening estimate only.A licensed window installer and your local building code are authoritative for final sizing, egress compliance, and product selection. Confirm every result with a pro and your local code.

Screening result

Enter both U-factors to compare relative conductive heat loss.

Fine Print and Sources

Screening estimate only. These tools use only the values you enter and simple planning math. A licensed window installer and your local building code are authoritative for final sizing, egress compliance, product selection, and pricing. Confirm every result with a pro and your local code.

This tool reports the relative reduction in conductive heat loss as (1 minus new U-factor divided by current U-factor). It is a proportional comparison of the window U-factors only. It is not a dollar savings guarantee. Real energy use also depends on air leakage, solar heat gain, glass area, climate, and how the whole house performs.