U Value To RSI Calculator


Calculating the U-value to RSI (Resistance to Heat Flow) is crucial in determining the insulation efficiency of a material or structure. This article provides a convenient calculator along with detailed explanations and examples.

How to Use

Simply input the necessary values into the designated fields and click on the “Calculate” button to obtain the RSI value.


The formula for converting U-value to RSI is as follows:


  • RSI = Resistance to Heat Flow (in square meter kelvin per watt, m²·K/W)
  • U = U-value (in watts per square meter kelvin, W/m²·K)

Example Solve

Let’s say we have a U-value of 0.2 W/m²·K. To find the corresponding RSI value:


Q: What is the U-value?

A: The U-value, also known as the thermal transmittance, represents the rate of heat loss through a material or assembly.

Q: What is the RSI value?

A: The RSI value is the reciprocal of the U-value, denoting the resistance to heat flow of a material or structure.

Q: Why is calculating U-value to RSI important?

A: It helps in evaluating the thermal performance and energy efficiency of building materials and designs.

Q: What are typical U-value ranges for different materials?

A: U-values can vary widely, with lower values indicating better insulation. For example, single-pane windows may have U-values around 5.0 W/m²·K, while high-performance insulation can achieve U-values as low as 0.1 W/m²·K.


Converting U-value to RSI provides valuable insights into the thermal properties of building materials. With the provided calculator and explanations, users can efficiently assess insulation performance and make informed decisions in construction and energy efficiency projects.

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