Thermal resistance converter
Convert thermal resistance between K/W and the US units. This is the heatsink number, not the insulation R-value.
That's 4× as insulating as a large finned heatsink, while a small clip-on heatsink is 2.5× higher. A 10 W part on it would sit about 20 °C above ambient.
What it means
How well does it get rid of heat?
Heatsink ratings assume free air. Forced airflow can halve the figure, and a poor thermal interface can add more resistance than the heatsink removes.
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Your resistance in every unit
Learn
Three things worth knowing
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Rise = resistance × watts
It is Ohm’s law with heat: degrees in place of volts, watts in place of amps. Resistances in series add, which is why the interface paste matters.
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Borrowed from circuits
Treating heat flow as a current through resistances lets engineers use the same arithmetic they already know, and it is accurate enough for steady-state design.
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Not the same as R-value
Insulation R-value is per square meter of wall; thermal resistance is for one whole object. A heatsink has no area in its rating.
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Background
About thermal resistance
Thermal resistance says how many degrees hotter something runs per watt it has to get rid of. A heatsink rated 2 K/W holding a 10 W part will sit 20 °C above the air around it.
Because a kelvin and a degree Celsius are the same size of step, K/W and °C/W are identical — datasheets use them interchangeably.