Resistência Térmica
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
R = L/(kA)
About this calculator
The thermal resistance calculator determines a material's resistance to heat transfer based on its thickness, thermal conductivity, and area. The formula used is R = L / (k × A), where R is thermal resistance (in K/W), L is thickness (in meters), k is thermal conductivity (in W/(m·K)), and A is area (in m²). This tool is useful for engineers, architects, and construction professionals who need to evaluate the thermal insulation of walls, windows, or other components.
How to use: enter positive values for thickness, thermal conductivity, and area. The result is the thermal resistance, which indicates the opposition to heat flow. Example: a wall with 0.2 m thickness, conductivity 0.8 W/(m·K), and area 10 m² has R = 0.2 / (0.8 × 10) = 0.025 K/W. Higher resistance means better insulation.
When to use: ideal for energy efficiency projects, sizing thermal insulation in buildings, analyzing heat losses in industrial equipment, and comparing materials. Care: check units (meters, W/(m·K), m²) and avoid negative values. The total thermal resistance of a composite wall is the sum of the resistances of each layer.
Frequently asked questions
What does high thermal resistance mean?
It indicates the material greatly opposes heat flow, making it a good thermal insulator.
Can I use the calculator for any material?
Yes, as long as you have the thermal conductivity, thickness, and area values. Common materials have conductivity tables.
How to calculate thermal resistance of a multi-layer wall?
Calculate the resistance of each layer separately and then add the results. This calculator handles one layer at a time.
What is the difference between thermal resistance and thermal conductivity?
Thermal conductivity (k) is a material property; thermal resistance (R) depends on geometry (thickness and area).
Is the result unit correct?
Yes, the result is in K/W (kelvin per watt). You can convert to other units if needed, but the calculator uses SI.