Enter the pipe diameter (m), the operating head (m), and the head loss coefficient into the Siphon Flow Rate Calculator. The calculator will evaluate the Siphon Flow Rate. 

Siphon Flow Rate Formula

The following formula is used to calculate the Siphon Flow Rate. 

SF = pi/4 * D^2 * (2*g*h/HLC)^.5


  • SF is the Siphon Flow Rate (m^3/s)
  • D is the pipe diameter (m) 
  • h is the operating head (m) 
  • HLC is the head loss coefficient 

How to Calculate Siphon Flow Rate?

The following steps outline how to calculate the Siphon Flow Rate.

  1. First, determine the pipe diameter (m).
  2. Next, determine the operating head (m). 
  3. Next, determine the head loss coefficient. 
  4. Next, gather the formula from above = SF = pi/4 * D^2 * (2*g*h/HLC)^.5.
  5. Finally, calculate the Siphon Flow Rate.
  6. 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.

pipe diameter (m) = .25

operating head (m) = 6

head loss coefficient = 1.25

SF = pi/4 * D^2 * (2*g*h/HLC)^.5 =  ?