Pipes and Fluid Flow Velocities

Calculate fluid flow and pipe velocities 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)


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 (ft3/s, ft3/min)

pipe inside diameter (ft)

volume flow (US gal/min, gpm)

pipe inside diameter (in)

SI units

Fluid flow velocity in a circular pipe can be calculated with SI units as

v = 1.273 q / d2                            (2)


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

Related Topics

  • Fluid Mechanics - The study of fluids - liquids and gases. Involves velocity, pressure, density and temperature as functions of space and time
  • Fluid Flow and Pressure Drop - Pipe lines - fluid flow and pressure loss - water, sewer, steel pipes, pvc pipes, copper tubes and more
  • Pipe Sizing - Sizing steam and condensate pipes - pressure loss, recommended velocity, capacity and more

Related Documents

Tag Search

  • en: flow velocity pipes american units
  • es: tuberías de velocidad de flujo unidades estadounidenses
  • de: Strömungsgeschwindigkeit Rohre amerikanischen Einheiten

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