Enter the fluid velocity, pipe diameter, and kinematic viscosity into the calculator to determine the friction factor. A friction factor is a unitless measure of friction of a fluid moving through a pipe. It’s often used to help calculate energy loss as fluid moves through an opening.

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## Friction Factor Formula

The following formula is used to calculate the friction factor in laminar flow.

f = 64 / RE = 64 / (V*D/v)

- Where f is the friction factor
- V is the fluid velocity (m/s)
- D is the diameter of the pipe (m)
- v is the kinematic viscosity (m^2/s)

In the case of this formula, it can also be written as 64 / RE, where RE is Reynold’s number = V*D/v

## Friction Factor Definition

A friction factor is a measure of the friction force acting on a fluid moving through a pipe.

## Friction Factor Example

The following is an example of calculating a friction factor.

- First, determine the velocity of the fluid. Measure the velocity of the fluid or calculate it. For this example, we will assume a velocity of 25 m/s.
- Next, determine the diameter of the pipe. The pipe in this problem is said to be 25m in diameter.
- Next, determine the kinematic viscosity. Through empirical data or through published data on the fluid, we find the kinematic viscosity to be 10 m^2/s.
- Finally, calculate the friction factor using the formula. f = 64/(25*25/10) = 1.024.

## FAQ

**What is a friction factor?**

A friction factor is a unitless measure of friction of a fluid moving through a pipe. It’s often used to help calculate energy loss as fluid moves through an opening.

**What is Reynolds number?**

The Reynolds number is a number, similar to a friction factor, which is a measure of the resistance to flow due to internal resistance as a fluid moves through a pipe.