Natural gas calculator

calculation of natural gas pressure drop or flow rate

online since 2006

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
custom fluid properties
K factor for fittings, resistance coefficient
pipe surface roughness selection
select between gauge and absolute pressure
compressible isothermal flow
dry air isothermal flow
gas offtake flow
natural gas flow



When is this calculator suitable?

This calculator is designed to calculate the flow or pressure drop in gas pipelines and gas distribution networks.

You can use the calculator for flow rate and pressure drop calculation in a constant diameter, natural gas pipeline.

The calculator enables calculation when natural gas is considered as a compressible or incompressible fluid.

The calculator also includes a calculation of the pressure drop due to local resistances built into the pipeline - valves and fittings.

What are the calculator restrictions?

The change in pressure due to the height difference of the pipeline is not included in this version of the calculator

How is the calculation executed?

The calculation of pressure drop, flow rate and pipe diameter during compressible flow is by the formulas for isothermal gas flow.

It assumes that the temperature of the natural gas flow in long pipelines is constant.

The temperature of the natural gas in long pipelines is constant because natural gas recovers the drop in temperature through the heat exchange with the surrounding soil or air.

There are two ways to calculate compressible flow with a calculator: using the compressible isothermal equation and using the Renouard formula.

In the flow rate calculation scenario, the calculator calculates and shows the flow rate at standard conditions.

If you are calculating pressure drop, then you should enter the flow rate at standard conditions in the calculator.

Standard conditions are:

  • pressure p = 101325 Pa (14.7 psi), and
  • temperature 15°C (59°F) for metric units and 60°F for imperial units

The calculator also presents actual flow mean velocity in the pipeline for the specified pipe diameter.

When is this calculator not relevant?

The calculator is not suitable for situations where changes in pressure are extreme and sudden leading to adiabatic flow conditions.

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Preview ONLINE natural gas pressure drop and flow rate calculator


Calculator for flow rate and pressure drop calculation for natural gas - online version is under contruction and in progress. Preview current alfa version with limited functionality.

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.

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

NatGasGasQ, D, L, t, p1Δp

Example #16

Task: Calculate the pressure drop generated by the natural gas at a flow rate of 200 Sm3/h through a pipe with nominal diameter of 2 inch and a length of 200 m. The gas temperature is 5 C, the surface roughness of the pipeline is 0.02 mm. Along the pipeline are 5 elbows R=1.5D, 90 deg. Pressure on the pipeline start is 2 bar gauge.

Solution: Pressure drop is: 59.6 mbar

NatGasGasD, L, t, p1, p2, kr, KQ

Example #17

Task: Calculate the maximum natural gas flow through a pipe with nominal diameter of 3/4 inch and a length of 200 m. The available pressure from pipeline from which the pipeline starts is 500 mbar gauge. Pipeline is connected with the gas train that requires 200 mbar gauge pressure for operation. The internal roughness of the pipe surface is 0.01 mm. The pipeline has 6 pipe elbows 90 degrees and a radius of 1.5 D. The natural gas temperature is 15 C.

Solution: Flow rate is: 27 Sm3/h

NatGasGasQ, D, L, t, kr, K, p1Δp

Example #18

Task: Calculate the pressure drop that creates natural gas at a flow rate of 500 MMSCFD through a pipeline with the nominal diameter of 36", and the length of 4 miles, with an internal roughness of the pipe wall of 0.0005 in. Gas temperature 40 F and the pressure at the pipeline start is 700 psi.

Solution: Pressure drop is: 3.89 psi

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