Thermal Resistance

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Calculate the opposition to heat flow (R-value) offered by a material or system.

Material Properties

Thickness (d)

Thermal Conductivity (k)

W/(m·K)

Temp Difference (ΔT) - Optional

K / °C

Calculation Results

Enter thickness and conductivity

About this calculator

Quick Reference

RThermal Resistance

dMaterial Thickness

kThermal Conductivity

U1/R (Thermal Transmittance)

Overview

Thermal resistance (R) is a measure of a material's ability to resist heat flow. A higher R-value means better insulation properties. It is calculated by dividing the material's thickness by its thermal conductivity.

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Pro Tips

R-value = Thickness / Thermal Conductivity (R = d/k).
Fiberglass insulation has a conductivity of approx 0.04 W/mK.
In buildings, wall R-values are summed for all layers including air films.

Fun Facts

"The 'R' in R-value stands for Resistance."
"In the US, R-values are often given in IP units (ft²·°F·hr/BTU), while the rest of the world uses SI units (m²·K/W)."
"Vacuum insulation panels can have R-values over 10 times higher than traditional materials."

Formula: R = d / k