Calculate the Resistance R from the Thickness (e) and the Lambda (λ)

This calculator lets you calculate the thermal resistance of an insulation material from its thickness and the lambda, which is the thermal conductivity.

What is the goal of the calculator?

The calculation determines the efficiency of an insulation material in terms of thermal insulation.

How to use the calculator?

Thermal resistance R

Just enter the insulation thickness in centimeters and the lambda in W/m·K. Then press the Calculate button and the thermal resistance R is calculated automatically.

Lambda and thickness

You can calculate the lambda or the thickness by entering the two other values.

Formulas

The formula for calculating the thermal resistance R is:

R = ^e⁄_λ

The formula works the same for the lambda and the thickness:

λ = ^e⁄_R

e = ^R⁄_λ

Where:

• R is the thermal resistance in m²·K/W (RSI, the metric equivalent of the US R-value; 1 m²·K/W ≈ R-5.68 in US units)
• e is the insulation thickness in meters (the calculator converts centimeters to meters)
• λ is the thermal conductivity coefficient in W/m·K

Why use this calculator?

Calculating the thermal resistance, the thickness and the lambda is important when evaluating the efficiency of an insulation material in construction and renovation. These calculations make it possible to select the most suitable materials for optimal thermal insulation, reducing heat loss and saving energy.

Benefits of effective insulation

Properly calculated insulation can significantly reduce energy consumption for heating and air conditioning, leading to substantial savings on energy bills.

Save and export the results in PDF and CSV format

Your calculations are recorded in the calculator's history. If you wish, you can export the results in PDF or CSV format.

Clear the fields

You can clear the fields by clicking the Clear button or by pressing the M key on your keyboard.

Keyboard shortcuts

You can use the following keys:

m ⇝ Clear

c ⇝ Calculate