Convert R-Value to U-Value

• 1). Note the R-value that you wish to convert. This may be expressed in the form R-19 or simply as a number. Check that it is given in square feet-degrees F-hour per Btu.
  
  
• 2). Divide the R-value into 1 and note the result. For example, if the R-value is 19, the result is 0.0526.
  
  
• 3). Check your calculation. Record the result, which is the R-value converted to the U-value in Btu per square foot-degrees F-hour.
  
  

Convert Imperial to Metric

• 1). Note the R-value that you wish to convert. This may be expressed in the form R-19 or simply as a number. Check that it is given in square feet-degrees F-hour per Btu.
  
  
• 2). Multiply the R-value by 0.1762 and note the result. For example, if the R-value is 19, the result is 3.348.
  
  
• 3). Check your work. Record the result, which is the R-value converted to square meters-degrees Celsius per watt.