Built and fact-checked by the DocNectar team — see our editorial standards
Key Features
Instant Calculation
Get accurate results in real time with our optimized algorithm.
Mobile Friendly
Fully responsive design. Works on all devices & screen sizes.
Privacy Focused
Your data stays on your device. We don't store any inputs.
100% Free
No hidden costs. This tool is completely free forever.
Thermal conductivity — how well a material conducts heat — is measured in Watts per meter-kelvin in the SI system, but US building and insulation specifications commonly use BTU per hour-foot-°F instead. This calculator converts between Watts per meter-kelvin, BTU per hour-foot-°F, and calories per second-centimeter-°C.
Insulation and building material datasheets in the US almost always use the BTU-based unit, which can make direct comparison to SI-based engineering calculations difficult without converting first.
How it works
Enter a value, choose the unit you're converting from and to, and the calculator applies the standard conversion factor between Watts per meter-kelvin, BTU per hour-foot-°F, and calories per second-centimeter-°C.
- Enter value.
- Enter from.
- Enter to.
- Click Calculate to see your results.
Examples
A building insulation material
An insulation material rated at 0.03 BTU per hour-foot-°F converts to about 0.052 Watts per meter-kelvin, the SI-standard way it would appear in an engineering calculation.
Comparing material datasheets
A metal's thermal conductivity reported in the SI unit is converted to the BTU-based unit to compare against a US-based engineering reference table.
Who should use it
- Converting a building insulation material's thermal conductivity to compare international specifications.
- Comparing engineering material datasheets that use different thermal conductivity unit conventions.
Industry applications
- Building and construction engineering
- Materials science and thermal engineering
Advantages
- Covers SI, US imperial, and CGS thermal conductivity unit conventions.
- Shows the exact conversion factor used, not just the final answer.
- No account, subscription or watermark.
Limitations
- Converts thermal conductivity only — not R-value or thermal resistance, which also depend on material thickness.
Common mistakes to avoid
- Confusing thermal conductivity with R-value, which is a related but inverse measure specific to a material's thickness.
- Mixing up thermal conductivity with specific heat capacity, which measures a different thermal property entirely.
Best practices
- Confirm which specific thermal property (conductivity, resistivity, or R-value) a datasheet is actually reporting before converting.
- Use Watts per meter-kelvin as your reference unit when comparing across international engineering sources.
Tips
- Lower thermal conductivity means better insulation — keep this in mind when comparing converted values.
- Double-check whether a source means thermal conductivity or the related but distinct R-value before converting.