Pipes - Fluid Flow Velocities
Calculate fluid velocity and volume flow in pipes and tubes.
Imperial units
Fluid flow velocity in a circular pipe can be calculated with Imperial or American units as
v = 1.273 q / d2
= 0.4084 qgpm / din2 (1)
where
v = velocity (ft/min, ft/s)
q = volume flow (ft3/s, ft3/min)
d = pipe inside diameter (ft)
qgpm = volume flow (US gal/min, gpm)
din = pipe inside diameter (inches)
Online Pipe Velocity Calculator - Imperial Units
volume flow (US gal/min, gpm)
pipe inside diameter (in)
Dimensions: Steel Pipes schedule 40 & 80, PVC and CPVC Pipes Schedule 40 & 80, Copper Tubes and PEX Tubes
volume flow (ft3/s, ft3/min)
pipe inside diameter (ft)
SI units
Fluid flow velocity in a circular pipe can be calculated with SI units as
v = 1.273 q / d2 (2)
where
v = velocity (m/s)
q = volume flow (m3/s)
d = pipe inside diameter (m)
Online Pipe Velocity Calculator - SI Units
volume flow (m3/s)
pipe inside diameter (m)
Example - Flow Velocity in a Steel Pipe
60 US gal/min is flowing through a 4 inch schedule 80 steel pipe. The internal diameter of the pipe is 3.83 in. The velocity can be calculated as
v = 0.4085 (60 gal/min) / (3.83 in)2
= 1.7 ft/s