Heat transfer coefficient converter
Convert between W/m²·K and the imperial form, the numbers behind radiators, heat exchangers and cooling fins.
That's about the same as moving air. With 10 °C across it, that moves about 250 W per square meter.
What it means
How fast does heat leave?
Values depend strongly on flow speed, surface shape and whether the fluid changes phase.
Every unit
Your coefficient in every unit
Learn
Three things worth knowing
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Move the fluid, multiply the heat
A fan over the same radiator can raise h five-fold. That is why every computer, car and boiler has something blowing or pumping.
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Newton’s law of cooling
Newton proposed that a body loses heat in proportion to the temperature difference. The constant of proportionality is exactly this coefficient.
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h is not a material property
Conductivity belongs to a material; h belongs to a situation. Change the airflow and the same surface gets a different number.
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Popular heat transfer coefficient conversions
Background
About heat transfer coefficients
The coefficient h describes heat moving between a surface and the fluid touching it: watts per square meter, per kelvin of difference.
Still air is a poor partner at about 5, moving water is 500, and boiling or condensing water reaches thousands, because changing phase carries enormous energy.