Enter the Grashof number  and the Prandtl number into the Rayleigh Number Calculator. The calculator will evaluate the Rayleigh Number. 

Rayleigh Number Formula

The following two example problems outline the steps and information needed to calculate the Rayleigh Number.

RN = GN * PN


  • RN is the Rayleigh Number ( )
  • GN is the Grashof number  
  • PN is the Prandtl number 

How to Calculate Rayleigh Number?

The following steps outline how to calculate the Rayleigh Number.

  1. First, determine the Grashof number . 
  2. Next, determine the Prandtl number. 
  3. Next, gather the formula from above = RN = GN * PN.
  4. Finally, calculate the Rayleigh Number.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

Grashof number  = 2.5

Prandtl number = 3.75

RN = GN * PN = ?