Created By : awnish

Reviewed By : Rajashekhar Valipishetty

Last Updated : Apr 10, 2023


Biot Number Calculator is an online tool used for computing the biot number on providing the inputs such as characteristic length, heat transfer coefficient, thermal conductivity, etc. in the allotted input fields. Make your computations much faster and get the biot number in a fraction of seconds.

Choose a Calculation:
Heat transfer coefficient
Thermal conductivity
Biot number

What is Biot Number?

Biot Number evaluates how quick is the heat transfer from the surface to its interior. It tells us how the temperature inside a body vary on heating a part of a surface. If the Temperature on Surface and Interior is Small then both the temperatureon surface, interior are almost similar. If Biot Number is large i.e. >1 then there will be a huge temperature gradient inside the body.

Heat Transfer | What is Biot Number Used for?

On heating a surface two things happen in general i.e. the surface gets warmed, heat transfers from surface to the rest of the material having its interior. However, the efficiency of the process depends on the heat coefficient.

Biot Number is used to compare the efficiency of both these processes. If the heat transfer is more efficient than thermal conductivity the surface gets faster than the rest of the body(Biot Number is Larger than 1). However, if the material conducts well then along with warming up the surface in one place the temperaure remains uniform(Biot Number is Smaller than 1).

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Biot Number Formula

Biot Number Formula is given by the Expression Bi = Lc * h / k

  • Where Lc [m] is the characteristic length of the material
  • h [W/(m² * K)] is the heat transfer coefficient on the surface
  • k [W/(m * K)] is the thermal conductivity of the material
  • Bi is the Biot Number

We can find the Characteristic Length Lc is we know the Volume V, Area of a Surface A through which the material is heated or cooled down. Lc = V / A

FAQs on Biot Number Calculator

1. What does the Biot Number Compare?

Biot Number Compares the heat transfer inside the body to heat transfer from the surface of the body.


2. Is Biot Number Dimensionless?

Yes, Biot Number is a Dimensionless Quantity and is used in Heat Transfer Calculations.


3. How is Biot Number Calculated?

You can compute the Biot Number using the formula Bi = Lc * h / k


4. What is the Biot Number Used for?

Biot Number is used for providing a direct indication regarding the importance of conduction and convection in determining the temperature of a body being heated or cooled by convection at its surface.