Pressure drop
Delta P = f (L / D) rho v^2 / 2
Fluid dynamics calculator
Darcy-Weisbach Calculator
Estimate pressure drop from friction factor, pipe length, diameter, density, and velocity.
Calculator
Enter values
Choose units beside each input. Results update automatically.
Result
About this calculator
How it works
The Darcy-Weisbach equation is a general pipe-flow relation for friction losses in closed conduits.
Formulas
Formulas used
Head loss
hf = Delta P / (rho g)
Guide
How to use this calculator
- Enter the known flow, geometry, or fluid property values.
- Select the units beside each input where a unit menu is shown.
- Read the highlighted result first, then use the table for supporting values.
Reference
What the results mean
Pressure drop
Pressure lost because of pipe wall friction.
Head loss
Friction loss expressed as equivalent fluid height.
FAQ
Darcy-Weisbach Calculator questions
Can I use different units?
Yes. Select the unit beside each input. The calculator converts values internally before solving.
Are these results suitable for final design?
Use results for education, screening, and early design checks. Verify final work against standards, codes, and project requirements.
Why do fluid results depend so much on assumptions?
Fluid calculations depend on geometry, roughness, density, viscosity, coefficients, and flow regime. Use representative input values and confirm assumptions.
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