R Value RSI and U Value Converter
Convert area-specific US R, metric RSI and corresponding U-values for one stated assembly.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Normalize positive area-specific resistance to RSI and take reciprocals for matching U-values.
RSI=R×(0.3048²×3600×5/9)/1055.05585262; U_SI=1/RSI
Worked example
R-20 is about RSI 3.52220367 m²·K/W, corresponding to U≈0.283913167 W/(m²·K) for the same stated resistance.
Assumptions and input details
Use the entire stated assembly value, not R per inch, conductivity or whole-object K/W resistance. U=1/R is valid only for matching area and boundary conventions. No surface film, bridge, installation effect, required code level or insulation recommendation is added.
References: Natural Resources Canada: R-value to RSI relationship
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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