Enter the flow rate, diameter, length, and friction factor into the calculator to determine the head loss in a pipe.

Head Loss Formula

The following formula is used to calculate the head loss in a pipe.

HL = (f * L * V^2) / (2 * g * D)

Variables:

  • HL is the head loss (feet)
  • f is the friction factor (dimensionless)
  • L is the length of the pipe (feet)
  • V is the velocity of the fluid (feet per second)
  • g is the acceleration due to gravity (32.2 ft/s²)
  • D is the diameter of the pipe (feet)

To calculate the head loss, first determine the velocity of the fluid through the pipe using the flow rate and diameter. Then, use the friction factor, length of the pipe, and the velocity to calculate the head loss using the formula provided.

What is Head Loss?

Head loss is the reduction in the total head (sum of pressure head, velocity head, and elevation head) of the fluid as it moves through a fluid system. This loss is due to the friction between the fluid and the pipe walls, as well as the friction between the fluid particles themselves as they flow. It is an important factor in the design and analysis of fluid systems such as water supply networks, heating systems, and chemical processes.

How to Calculate Head Loss?

The following steps outline how to calculate the Head Loss.


  1. First, determine the flow rate (Q) in gallons per minute.
  2. Next, determine the diameter of the pipe (D) in inches.
  3. Next, determine the length of the pipe (L) in feet.
  4. Next, determine the friction factor (f), which is dimensionless.
  5. Next, calculate the velocity (V) of the fluid using the flow rate and diameter.
  6. Finally, calculate the Head Loss (HL) in feet using the formula provided.
  7. 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.

flow rate (Q) = 100 gallons per minute

diameter of the pipe (D) = 6 inches

length of the pipe (L) = 100 feet

friction factor (f) = 0.02