Window calculators & converters
Free, no-signup tools for US builders and architects working with European windows - unit conversions and cost estimates I reach for on real projects.
U-Value / U-Factor to R-Value Calculator & Converter
Calculate a window's R-value from its U-value or U-factor, or go from R-value to U-value - metric W/m2K accepted - with single, double, and triple-glazed reference values.
Open tool →Metric U-Value to Imperial U-Factor
Convert European metric U-value (W/m2K) to US imperial U-factor - the spec check every import project needs.
Open tool →European Window Cost Estimator
Enter your areas and get a live landed-cost range across three tiers, duties and freight included.
Open tool →