Plumbers usually measure flow rates in terms of the volume of water that passes each minute. Convert this value to velocity using the pipe's size.

Step 1 Step 2 Step 3

Multiply flow rate in gallons per minute by 0.408. For instance, if the flow rate is 50 gal / min: 50 * 0.408 = 20.4

Square the pipe's diameter, in inches. For instance, if the pipe measures 4 inches across: 4 * 4 = 16

Divide the answer to step 1 by the answer to step 2. 20.4 / 16 = 1.275 This answer is the water velocity in feet per minute.

#### Things You Will Need

- Calculator or computer

#### Resources

#### Photo Credits

- water pipe image by jeancliclac from Fotolia.com