R-Value to RSI and U-Factor Converter
Canadian codes publish RSI (m²·K/W) while product labels often show imperial R-values. U-factor is the reciprocal of total resistance.
Free tool
Result
Enter values to calculate.
Formula
- RSI = R × 0.1761
- R = RSI × 5.678
- U = 1 ÷ R
Example calculation
R-20 = RSI 3.52; U = 0.05 BTU/h·ft²·°F (0.284 W/m²·K).
Practical HVAC use
Check insulation against code tables, compare products, and feed U-factors into heat loss calculations.
Common mistakes
- Adding U-factors of layers instead of adding R-values.
- Using cavity R-value as the whole-wall value — framing lowers it.
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Educational tool. Results are estimates from the stated formulas; always confirm with manufacturer data and the code adopted in your jurisdiction. All calculators