Conversion method
Thermal conductivity is a material property; it is distinct from conductance and heat-transfer coefficient. Temperature units denote intervals. BTU uses the International Table definition.
BTU IT·ft/(h·ft²·°F) = x × 0.5777893165429983
10 W/(m·K) = 5.777893 BTU IT·ft/(h·ft²·°F).
| W/(m·K) | BTU IT·ft/(h·ft²·°F) |
|---|---|
| 1 | 0.577789 |
| 5 | 2.888947 |
| 10 | 5.777893 |
| 25 | 14.444733 |
| 50 | 28.889466 |
| 100 | 57.778932 |
Unit definitions and sources
Thermal conductivity is a material property; it is distinct from conductance and heat-transfer coefficient. Temperature units denote intervals. BTU uses the International Table definition.
| Unit and system | Use | Definition | Relationship |
|---|---|---|---|
| Watt per meter kelvin (W/(m·K)); si | Common units | Watt per meter kelvin: base (w-m-k) = value × 1. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| BTU (IT) foot per hour square foot Fahrenheit (BTU IT·ft/(h·ft²·°F)); si | Common units | BTU (IT) foot per hour square foot Fahrenheit: base (w-m-k) = value × 1.730734666371391. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Watt per centimeter kelvin (W/(cm·K)); si | Specialist units | Watt per centimeter kelvin: base (w-m-k) = value × 100. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Thermochemical calorie per centimeter second kelvin (cal th/(cm·s·K)); si | Specialist units | Thermochemical calorie per centimeter second kelvin: base (w-m-k) = value × 418.4. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Watt/meter/K (W/(m)/(K)); other | Specialist units | watt/meter/K = 1.0 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Watt/centimeter/°C (W/(cm)/(K)); other | Specialist units | watt/centimeter/°C = 100.0 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Kilowatt/meter/K (kW/(m)/(K)); other | Specialist units | kilowatt/meter/K = 1000.0 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Calorie (IT)/second/cm/°C (cal IT/(s)/(cm)/(K)); other | Specialist units | calorie (IT)/second/cm/°C = 418.67999999999995 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Calorie (th)/second/cm/°C (cal th/(s)/(cm)/(K)); other | Specialist units | calorie (th)/second/cm/°C = 418.40000000000003 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Kilocalorie (IT)/hour/meter/°C (kcal IT/(h)/(m)/(K)); other | Specialist units | kilocalorie (IT)/hour/meter/°C = 1.163 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Kilocalorie (th)/hour/meter/°C (kcal th/(h)/(m)/(K)); other | Specialist units | kilocalorie (th)/hour/meter/°C = 1.1622222222222223 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Btu (IT) inch/second/sq. foot/°F (BTU IT·in/(s)/(ft²)/(Δ°F)); other | Specialist units | Btu (IT) inch/second/sq. foot/°F = 519.2203999114172 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Btu (th) inch/second/sq. foot/°F (BTU th·in/(s)/(ft²)/(Δ°F)); other | Specialist units | Btu (th) inch/second/sq. foot/°F = 518.8731616579175 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Btu (IT) foot/hour/sq. foot/°F (BTU IT·ft/(h)/(ft²)/(Δ°F)); other | Specialist units | Btu (IT) foot/hour/sq. foot/°F = 1.730734666371391 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Btu (th) foot/hour/sq. foot/°F (BTU th·ft/(h)/(ft²)/(Δ°F)); other | Specialist units | Btu (th) foot/hour/sq. foot/°F = 1.7295772055263923 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Btu (IT) inch/hour/sq. foot/°F (BTU IT·in/(h)/(ft²)/(Δ°F)); other | Specialist units | Btu (IT) inch/hour/sq. foot/°F = 0.14422788886428256 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
| Btu (th) inch/hour/sq. foot/°F (BTU th·in/(h)/(ft²)/(Δ°F)); other | Specialist units | Btu (th) inch/hour/sq. foot/°F = 0.144131433793866 w-m-k, derived from the component SI/customary definitions. Common use: Thermal Conductivity. Source checked 2026-09-20 (implementation review). | Exact definition; numerical display may be rounded |
Sources: NIST: SP 811 Appendix B.8: conversion factors; BIPM: SI prefixes
Precision of thermal conductivity conversions
All 17 thermal conductivity units convert through Watt per meter kelvin (W/(m·K)). 17 have an exact defined relationship to the base unit and 0 are conventional or measured values. Results and the tables on this page come from the same engine, so a table value can be checked against the converter directly.
Standard display shows up to six decimal places, switching to scientific notation for very large or small values. Calculation uses JavaScript binary floating point independently of display rounding, so extra digits are not a claim about measurement accuracy. Each unit lists its own source; a citation records where the definition comes from, not an independent review. See Conversion methodology for the review and correction process.