Pipe diameter and flow rate calculator

round, closed, full pipe diameter calculation

online since 2007

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Calculation setup
Flow rates and velocity
Pipe dimensions
Fluid properties

Exclusive calculator

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Calculator description

Read more about calculator application and check if calculator is suitable for your problem.

Also, read about calculation procedures, what you have to know for the calculations and what limitations apply.


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Available in download version

save/open multiple results
export to word and excel
print results
custom fluid properties
K factor for fittings, resistance coefficient
select between gauge and absolute pressure
compressible isothermal flow
dry air isothermal flow
gas offtake flow
natural gas flow


Calculator start selection

Read all about available deployments. In any way of utilizing calculator, Internet connection is required, for authentication at least.

Issues and answers

Having problems with calculators usage? Read more about known issues and problems and way to solve it.

issues and answers


q - volumetric flow rate
Fluid flow rate in terms of units of volume per unit of time
ṁ - mass flow rate
Fluid flow rate in terms of units of mass per unit of time
D - pipe diameter
Internal circular pipe diameter
V - velocity
Flow velocity in terms of units of distance per unit of time
A - area
Internal pipe cross section area
ρ - fluid density
Mass per unit of volume
T - temperature
Fluid temperature for gas density calculation based on the ideal gas state equation
p - pressure
Fluid pressure at the start of the pipe for gas density calculation based on the ideal gas state equation
R - gas constant
Gas constant in terms of energy per unit of mass and temperature, for gas density calculation using ideal gas state equation

Calculation setup

Select value to calculate. You should enter not selected one.
pipe diameter
flow velocity
Select value to input. You should enter selected one. The other one will be calculated
volumetric flow rate
mass flow rate
Select value to input. You should enter selected one. The other one will be calculated. Available only if the gas is selected fluid
fluid density
Select fluid type
for incompressible fluids
for fluids where ideal gas state equation is used. Enables selection between density and temperature to input.
Select pipe shape
round pipe
full cross section fluid flow
rectangle pipe
for rectangle channels and full cross section flow

Watch how calculator can help you resolve task in less than a minute

PipDiaWaterQ, vD

Example #1

Task: Calculate the pipe diameter if the water flow velocity is 1 m/s and the flow rate is 5 lit/min.

Solution: Pipe diameter is 10.3 mm

PipDiaAirQ, Dv

Example #2

Task: Calculate the airflow velocity if the inner diameter of the pipe is 50 mm and the flow rate is 100 m3/h at a pressure of 3 bar absolute and a temperature of 15 °C

Solution: Flow velocity is 14.15 m/s

PipDiaCarbon dioxideQ, vD

Example #3

Task: Calculate the diameter of the carbon dioxide pipe with a flow rate of 10 kg/h and a velocity 2 m/s at a pressure of 7 bar absolute and a temperature of 20 °C.

Solution: Pipe diameter is 11.8 mm

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