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Pressure Drop Calculator

Compute segment pressure drop with direct or calculated Darcy friction factor and CFD geometry inputs.

Pressure Drop inputs

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Geometry

Geometry mode

Geometry length unit

Diameter

Flow input

Flow input mode

Velocity

Velocity unit

Fluid properties

Fluid property mode

Fluid preset

Viscosity mode

Density

Density unit

Kinematic viscosity

Kinematic viscosity unit

Water near 20 °C, 20 °C, approximately 1 atm. Water properties vary with temperature, pressure, dissolved material, and source. Override the preset for real design or validation work.

Friction factor

Friction-factor mode

Darcy friction factor

Pressure-loss segment

Segment length

Segment length unit

Total minor-loss coefficient K

Gravity

m/s^2, default standard gravity.

Pressure output unit

Display precision

Result section

warningUser-supplied Darcy friction factor

Total pressure drop

4,000 Pa

Secondary results

Major pressure drop: 4,000 Pa
Minor pressure drop: 0 Pa
Head loss: 0.407886 m
Velocity: 2 m/s
Darcy friction factor: 0.02
Dynamic pressure: 2,000 Pa

Unit conversion summary

Unit-normalization summary: 10 m; 0.1 m; 1,000 kg/m^3; 4,000 Pa

Warnings

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.
Fluid presets are starter values only; verify properties at the actual operating condition.
This is not a complete piping-network solver and does not include elevation, pumps, turbines, cavitation, phase change, or transient effects.

Assumptions

Incompressible constant-density Darcy-Weisbach segment loss.
Minor-loss coefficient is user supplied and not drawn from a fittings database.

Calculation steps

Resolve velocity2 m/s
Resolve friction factor0.02
Calculate major loss4,000 Pa
Calculate minor loss0 Pa
Calculate head loss0.407886 m

Darcy-Weisbach pressure drop

\Delta P = f_D (L/D_h)(\rho V^2/2) + K(\rho V^2/2)

DeltaP_total = f_D (L/D_h) (rho V^2/2) + K (rho V^2/2)

DeltaP_major = 0.02 x (10 m / 0.1 m) x 2,000 Pa

Technical visual

Technical sketch for pressure drop calculator. Values are illustrative; calculated values appear in the result section.

Engineering interpretation

Major and minor losses are separated so the frictional segment loss can be reviewed before adding user-specified local loss coefficients.

What is the pressure drop calculator?

Calculate frictional pressure loss in an internal-flow segment using the Darcy-Weisbach equation with optional minor-loss coefficients.

How to use the pressure drop calculator

Select the calculation mode that matches the data you already have.
Enter values with units; the calculator normalizes inputs to SI internally.
Review derived values, warnings, formulas, and assumptions before using the result in another CFD step.
Use the pressure converter link when you need kPa, bar, or psi output.

Input explanations

Geometry inputs are used to derive hydraulic diameter, cross-sectional area, or characteristic length where needed.
Flow input modes derive velocity from direct velocity, volumetric flow rate, or mass flow rate when applicable.
Dynamic viscosity uses density to derive kinematic viscosity; kinematic viscosity can be used directly where density is mathematically unnecessary.
Fluid presets are starter values only and can be overridden manually.

Notation

Formula notation
Symbol	Meaning	Unit
Delta P	Pressure drop	Pa
f_D	Darcy friction factor	dimensionless
L	Segment length	m
D_h	Hydraulic diameter	m
K	Total minor-loss coefficient	dimensionless

Worked examples

Major loss: f_D = 0.02, L = 10 m, D_h = 0.1 m, rho = 1000 kg/m^3, V = 2 m/s gives 4000 Pa.

Minor loss: K = 2 and dynamic pressure = 2000 Pa adds 4000 Pa.

Head loss: 4000 Pa at rho = 1000 kg/m^3 and g = 9.80665 m/s^2 gives 0.407886 m.

Cross-tool workflow

The Pressure Drop Calculator separates major frictional loss from optional minor-loss K values and reports head loss.

Convert pressure units

Common mistakes

Treating this as a full pipe-network solver.
Using minor-loss K values outside their documented context.
Ignoring gas compressibility when density changes significantly.
Mixing Darcy and Fanning friction factors.

Limitations

Elevation, pumps, turbines, cavitation, phase change, and transient effects are not included.
The equation is an incompressible constant-density segment-loss estimate.
No fittings database is included.

References

White Fluid Mechanics: White, F. M., Fluid Mechanics, McGraw-Hill.
Fox and McDonald Fluid Mechanics: Fox, McDonald, and Pritchard, Introduction to Fluid Mechanics, Wiley.
Versteeg and Malalasekera CFD: Versteeg, H. K. and Malalasekera, W., An Introduction to Computational Fluid Dynamics, Pearson.
Pope Turbulent Flows: Pope, S. B., Turbulent Flows, Cambridge University Press.
NASA Turbulence Modeling Resource: NASA Langley Research Center, Turbulence Modeling Resource.

What is the Darcy-Weisbach equation?

It estimates major frictional pressure loss using f_D (L/D_h) (rho V^2/2).

Major versus minor losses?

Major loss is wall-friction loss along the segment; minor losses use user-entered K coefficients for local elements.

Pressure drop versus head loss?

Head loss is pressure drop divided by rho g and is reported in meters of fluid.

Does this tool work for gases?

It can estimate constant-density gas losses, but significant compressibility needs a different model.

How is velocity calculated from flow rate?

Volumetric flow uses V = Q/A and mass flow uses V = m_dot/(rho A).

Can friction factor be calculated?

Yes. It can use Reynolds number and roughness or derive Reynolds number from fluid and flow inputs.

Are fittings included?

No database is included; enter total K only when you have a justified value.

Professional support from ScholarEase Consultancy Services LLP

Professional CFD, simulation setup, engineering calculations, technical documentation, and research support are available through the connected services website. These calculators remain free to use without purchasing services.

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Engineering disclaimer

This tool is intended for educational, estimation, and preliminary CFD setup support. Always verify critical engineering calculations with applicable standards, validated software, solver documentation, and qualified professional judgment.

Need Professional Support?

ScholarTool is powered by ScholarEase Consultancy Services LLP. Professional engineering, simulation, research, and technical documentation support is available through the connected services website.

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Last reviewed: 2026-06-19

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Pressure Drop inputs

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.

Geometry

Geometry mode

Geometry length unit

Diameter

Flow input

Flow input mode

Velocity

Velocity unit

Fluid properties

Fluid property mode

Fluid preset

Viscosity mode

Density

Density unit

Kinematic viscosity

Kinematic viscosity unit

Water near 20 °C, 20 °C, approximately 1 atm. Water properties vary with temperature, pressure, dissolved material, and source. Override the preset for real design or validation work.

Friction factor

Friction-factor mode

Darcy friction factor

Pressure-loss segment

Segment length

Segment length unit

Total minor-loss coefficient K

Gravity

m/s^2, default standard gravity.

Pressure output unit

Display precision

Result section

warningUser-supplied Darcy friction factor

Total pressure drop

4,000 Pa

Secondary results

Major pressure drop: 4,000 Pa
Minor pressure drop: 0 Pa
Head loss: 0.407886 m
Velocity: 2 m/s
Darcy friction factor: 0.02
Dynamic pressure: 2,000 Pa

Unit conversion summary

Unit-normalization summary: 10 m; 0.1 m; 1,000 kg/m^3; 4,000 Pa

Warnings

Calculations are performed locally in your browser and are not submitted to a third-party calculation API.
Fluid presets are starter values only; verify properties at the actual operating condition.
This is not a complete piping-network solver and does not include elevation, pumps, turbines, cavitation, phase change, or transient effects.

Assumptions

Incompressible constant-density Darcy-Weisbach segment loss.
Minor-loss coefficient is user supplied and not drawn from a fittings database.

Calculation steps

Resolve velocity2 m/s
Resolve friction factor0.02
Calculate major loss4,000 Pa
Calculate minor loss0 Pa
Calculate head loss0.407886 m

Darcy-Weisbach pressure drop

\Delta P = f_D (L/D_h)(\rho V^2/2) + K(\rho V^2/2)

DeltaP_total = f_D (L/D_h) (rho V^2/2) + K (rho V^2/2)

DeltaP_major = 0.02 x (10 m / 0.1 m) x 2,000 Pa

Technical visual

Technical sketch for pressure drop calculator. Values are illustrative; calculated values appear in the result section.

How to use the pressure drop calculator

Select the calculation mode that matches the data you already have.
Enter values with units; the calculator normalizes inputs to SI internally.
Review derived values, warnings, formulas, and assumptions before using the result in another CFD step.
Use the pressure converter link when you need kPa, bar, or psi output.

Input explanations

Geometry inputs are used to derive hydraulic diameter, cross-sectional area, or characteristic length where needed.
Flow input modes derive velocity from direct velocity, volumetric flow rate, or mass flow rate when applicable.
Dynamic viscosity uses density to derive kinematic viscosity; kinematic viscosity can be used directly where density is mathematically unnecessary.
Fluid presets are starter values only and can be overridden manually.

Symbol

Meaning

Unit

Delta P

Pressure drop

f_D

Darcy friction factor

dimensionless

Segment length

D_h

Hydraulic diameter

Total minor-loss coefficient

dimensionless

References

White Fluid Mechanics: White, F. M., Fluid Mechanics, McGraw-Hill.

Fox and McDonald Fluid Mechanics: Fox, McDonald, and Pritchard, Introduction to Fluid Mechanics, Wiley.

Versteeg and Malalasekera CFD: Versteeg, H. K. and Malalasekera, W., An Introduction to Computational Fluid Dynamics, Pearson.

Pope Turbulent Flows: Pope, S. B., Turbulent Flows, Cambridge University Press.

NASA Turbulence Modeling Resource: NASA Langley Research Center, Turbulence Modeling Resource.

Pressure Drop inputs

Geometry

Flow input

Fluid properties

Friction factor

Pressure-loss segment

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Darcy-Weisbach pressure drop

Technical visual

Engineering interpretation

What is the pressure drop calculator?

How to use the pressure drop calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Professional support from ScholarEase Consultancy Services LLP

Print summary

Engineering disclaimer

Need Professional Support?

Pressure Drop inputs

Geometry

Flow input

Fluid properties

Friction factor

Pressure-loss segment

Result section

Secondary results

Unit conversion summary

Warnings

Assumptions

Calculation steps

Darcy-Weisbach pressure drop

Technical visual

Engineering interpretation

What is the pressure drop calculator?

How to use the pressure drop calculator

Input explanations

Notation

Worked examples

Cross-tool workflow

Common mistakes

Limitations

References

Related tools

Professional support from ScholarEase Consultancy Services LLP

Print summary

Engineering disclaimer

Need Professional Support?