Calculator
What the Thermal Conductivity Converter does
Thermal Conductivity Converter: 1 W/(m·K) = 0.57778921 BTU/(h·ft·°F), so multiply a watt per metre kelvin value by 0.57778921 to get BTU per hour foot °F, or divide to go back. Example: 1 W/(m·K) = 0.57778921 BTU/(h·ft·°F).
Point it at Value, From and To and it returns Result, How it was calculated and Reverse conversion. The result recalculates on every keystroke without a button press or a page reload.
It is mostly used by people following a recipe or spec written elsewhere. Two industries often use the same word for slightly different quantities.
Everything happens inside this page. Nothing you type is sent to a server, and there is nothing for us to store.
The sections that follow cover the fields, the method, and one full example computed from the defaults.
What do the Thermal Conductivity Converter fields mean?
The Thermal Conductivity Converter uses 3 inputs. The form opens pre-filled, so the fastest way in is usually to overwrite the one field you actually care about.
| Field | What to enter | Default |
|---|---|---|
| Value | required | 1 |
| From | choose from Watt per metre kelvin (W/(m·K)), Kilocalorie per hour metre °C (kcal/(h·m·°C)), BTU per hour foot °F (BTU/(h·ft·°F)) or BTU inch per hour ft² °F (BTU·in/(h·ft²·°F)) | Watt per metre kelvin (W/(m·K)) |
| To | choose from Watt per metre kelvin (W/(m·K)), Kilocalorie per hour metre °C (kcal/(h·m·°C)), BTU per hour foot °F (BTU/(h·ft·°F)) or BTU inch per hour ft² °F (BTU·in/(h·ft²·°F)) | BTU per hour foot °F (BTU/(h·ft·°F)) |
How does the Thermal Conductivity Converter work?
Both units are converted through thermal conductivity's base unit (W/(m·K)), so any of the 4 units in the dropdowns can be paired in either direction without loss of accuracy.
Definitions are taken from the SI system where one exists, and from CODATA or the IAU where a unit is established by measurement. No factor is rounded before the calculation.
Worked example
These are the values the Thermal Conductivity Converter loads by default, and the result it produces from them. These are the tool’s own default values and the result they produce, not an invented illustration.
| Value | 1 |
|---|---|
| From | Watt per metre kelvin (W/(m·K)) |
| To | BTU per hour foot °F (BTU/(h·ft·°F)) |
| Result | 0.57778921 BTU/(h·ft·°F) |
|---|---|
| How it was calculated | 1 W/(m·K) = 0.57778921 BTU/(h·ft·°F), so 1 × 0.57778921 = 0.57778921 BTU/(h·ft·°F) |
| Reverse conversion | 1.730735 W/(m·K) (if you meant 1 BTU/(h·ft·°F)) |
Thermal conductivity
Thermal conductivity measures how readily a material conducts heat, in watts per metre-kelvin (W/(m·K)), but the US building and insulation industry instead markets products by R-value, which runs in the opposite direction: R-value measures resistance to heat flow, so a higher R-value means better insulation, the reverse of a higher thermal-conductivity number.
Worth knowing
- Because R-value and thermal conductivity are inversely related (and R-value also folds in material thickness, unlike raw conductivity), the two numbers cannot be compared directly without doing the actual inversion and unit conversion: a genuinely common point of confusion between US insulation shopping and international thermal-conductivity specifications.
- Metals are excellent thermal conductors (copper is around 400 W/(m·K)), while good insulating materials like fibreglass or foam are around 0.03 to 0.04 W/(m·K): a difference of roughly four orders of magnitude between the best conductors and the best insulators in everyday use.
- This property is distinct from the heat transfer coefficient (covered in its own converter), which describes heat moving between a surface and a moving fluid (convection) rather than heat moving through a solid material (conduction).
Definitions: BIPM SI Brochure · NIST reference on units
How to use it
- Enter Value.
- Pick a value for From: the options are Watt per metre kelvin (W/(m·K)), Kilocalorie per hour metre °C (kcal/(h·m·°C)), BTU per hour foot °F (BTU/(h·ft·°F)) or BTU inch per hour ft² °F (BTU·in/(h·ft²·°F)).
- Pick a value for To: the options are Watt per metre kelvin (W/(m·K)), Kilocalorie per hour metre °C (kcal/(h·m·°C)), BTU per hour foot °F (BTU/(h·ft·°F)) or BTU inch per hour ft² °F (BTU·in/(h·ft²·°F)).
- Because it recalculates as you type, you can dial a value in rather than guessing and re-running.
- You get Result, How it was calculated and Reverse conversion back.
- Both Copy Link and Print capture the current state, so pick whichever suits how you file things.
What this tool does not do
- Repeated conversions compound rounding, so convert once from the original value where you can.
- Conversion factors use SI definitions; some industries use their own rounded factors.
- The result reflects the moment you ran it; anything that changes over time is not tracked.
- Results are only as good as the inputs. Check your units before reading anything into the output.
Frequently asked questions
The form asks for Value, From and To. A starting value is in place for each, which means a single edit is enough to get a meaningful answer.
With the values loaded when the page opens, result comes out as 0.57778921 BTU/(h·ft·°F). It recalculates the moment an input changes, which makes comparing scenarios quick.
No. There is no upload step, no database, and nothing to delete afterwards.
It costs nothing, and there is no limit on repeat use.
Full double precision is used throughout; only the displayed figure is shortened.