Convert Btu (IT)·inches per Second per Sq. Foot per °F to Kilowatts per Meter per Kelvin

The Formula

Every unit here is defined by a fixed multiplier relative to watts per meter per kelvin. To convert a value from one unit to another:

result = value × (factor of "From" unit ÷ factor of "To" unit)

For Btu (IT)·inch per Second per Sq. Foot per °F → Kilowatt per Meter per Kelvin: multiply by 0.51922. For example, 1 Btu·in/(s·ft²·°F) × 0.51922 = 0.51922 kW/(m·K).

Conductivity (k) vs. Resistance (R)

Thermal conductivity (this page) is a property of the material itself, independent of how thick a piece of it you have. R-value, printed on US insulation packaging, is the inverse relationship scaled by an actual thickness — a thicker layer of the same material has a higher R-value even though its conductivity k hasn't changed. That's why doubling a wall's insulation thickness roughly doubles its R-value, but has no effect at all on the insulation material's underlying k-value in W/(m·K) or Btu·in/(h·ft²·°F).

Conductors vs. Insulators

Thermal conductivity spans an enormous range: solid copper conducts heat at roughly 400 W/(m·K), while modern aerogel insulation can be as low as 0.015 W/(m·K) — a difference of over 25,000 times. Materials engineers reach for this converter constantly when comparing candidate materials sourced from different countries' datasheets, since the same underlying physical property is reported in wildly different-looking numbers depending on the unit convention used.

Example

A material with a conductivity of 1 Btu·in/(s·ft²·°F) equals 0.51922 kW/(m·K). For scale, common fiberglass batt insulation sits around 0.04 W/(m·K), while structural concrete is roughly 1.7 W/(m·K) — over 40 times more conductive, which is why concrete alone provides negligible insulation value.

Frequently Asked Questions