Gas pressure drop calculator

calculation of isothermal gas pressure drop or flow rate

online since 2011

pipe flow calculator

Calculator start selection

Read all about available deployments. In any way of utilizing calculator, Internet connection is not required, but nice to have for authentication at least.

Available in download version

save/open multiple results
export to Word and Excel
print results
create list of custom fluid properties
resistance factor K for flow in valves and fittings
pipe surface roughness selection
pipe material selection
select between gauge and absolute pressure
compressible isothermal flow
dry air isothermal flow
gas offtake flow
natural gas flow


pipe network analysis

Why should you use this calculator?

With this calculator, you can calculate flow rate or pressure drop of any gas that flows through round closed pipe.

When is this calculator suitable?

This calculator is suitable for any gas including air, natural gas, methane, carbon dioxide, oxygen, nitrogen, or any other gas.

You can use this calculator for laminar and turbulent flow regime.

What are the calculator restrictions?

A temperature of the gas is considered to be constant, regardless of created pressure drop. This assumption is valid only for relatively long pipelines without any sudden changes and pipe thermal insulation. During slow, steady flow, if the temperature of the fluid drops due to the pressure drop, this calculation model assumes that fluid takes heat from the surrounding. This heat taken from the surrounding keeps the temperature of the flow in the pipeline constant.

How is the calculation executed?

The calculator uses a pressure drop equation for isothermal flow. To calculate the pressure drop, the calculator performs friction factor f and minor resistance coefficient K calculation, as well as the mean velocity of the flow on the pipe start and the pipe end.

The calculator includes Reynolds number (Re) calculation, as well as compressibility factor (Z) for gases that are not performing as ideal. Also, the calculation is performing friction losses (f) and minor losses factors (K), needed for pressure drop calculation.

Calculator presents values of Reynolds number and flow regime - laminar or turbulent, as well as calculated densities on the pipe start and the pipe end.

When is this calculator not relevant?

This calculator is not suitable for adiabatic flow when the temperature is changing due to the change of pressure. It means that you can't use this calculator where you expect for sudden changes pressure due to flow restrictions, sudden change of the flow direction and similar conditions. The calculator is not considering a change of the height in the calculation.

What else has to be known to perform the calculation?

For pressure drop calculation you must enter flow rate and pipe diameter. For flow rate calculation, you must enter pressure drop and pipe diameter also.

Need a helping hand?


If you need a quick calculation, but you are not still familiar how to use the calculator, you can order calculation service from the calculator developer.

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