Calculate the Biot number to determine the temperature uniformity within a body during heat transfer.
Heat Transfer Parameters
W/m²·K
W/m·K
Calculation Results
Enter parameters to calculate
About this calculator
Quick Reference
hConvective heat transfer coefficient
LCharacteristic length (Volume / Area)
kThermal conductivity of the body
Overview
The Biot number (Bi) is a dimensionless quantity used in heat transfer calculations. It provides an index of the ratio of the heat transfer resistances inside of and at the surface of a body.
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Pro Tips
Bi < 0.1 usually means the temperature inside the body is fairly uniform (lumped capacitance model).
For a sphere, L = Radius / 3. For a long cylinder, L = Radius / 2.
Units: h (W/m²·K), L (m), k (W/m·K).
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Fun Facts
"If Bi is very small, the body's internal thermal resistance is negligible compared to its surface resistance."
"Bi is named after Jean-Baptiste Biot, a French physicist who also studied magnetism (Biot-Savart law)."
"Cooking relies heavily on understanding how heat moves into food (high Bi vs low Bi)."
