Thermal Resistance Layers Calculator
Combine thermal resistance values for layers arranged in series and convert the total resistance to an equivalent U-value.
How to use this calculator
- Enter positive layer R-values separated by commas.
- Confirm that all inputs use the stated units and the same population, period or scope.
- Change one assumption at a time when comparing scenarios.
Formula used by the thermal resistance series calculator
Rtotal = ΣRᵢ; U = 1/Rtotal
- Rtotal = ΣRᵢ; U = 1/Rtotal
- One-dimensional steady heat flow is assumed; surface-film resistance and thermal bridges must be represented separately.
- Inputs are validated against required ranges and outputs are rounded for readability.
Worked examples
Worked example
Layers have R-values 0.5, 1.2 and 0.3 m²K/W.
Total R is 2.0 m²K/W and U is 0.5 W/m²K.
Total R is 2.0 m²K/W and U is 0.5 W/m²K.
Understanding the result
Combine thermal resistance values for layers arranged in series and convert the total resistance to an equivalent U-value.
One-dimensional steady heat flow is assumed; surface-film resistance and thermal bridges must be represented separately.
Important notes
One-dimensional steady heat flow is assumed; surface-film resistance and thermal bridges must be represented separately.
Use the result as a calculation aid for the inputs supplied; confirm critical specifications independently.
Frequently asked questions
Can I include surface resistance?
Yes, if you have the applicable values and ensure you do not double-count them elsewhere.
Does series include parallel paths?
No; parallel heat-flow paths require a different combined-resistance calculation.
How do I use this calculator?
Enter positive layer R-values separated by commas.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
- How to Calculate Percentage Change — Learn the percentage change formula, how to calculate increases and decreases, and why the original value matters.
- How to Calculate Percent Error — Learn the percent error formula and how to compare an experimental value with a reference or accepted value.
- Ohm's Law — Understand Ohm's law and the relationship between voltage, current, and resistance.
This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.