Pipe Friction Loss Calculator
Calculate pipe velocity, Reynolds number, Darcy friction factor, major and minor head loss, psi drop, equivalent fitting length, Hazen–Williams comparison and pump power.
Project inputs
Change any value to update the result. Units, boundaries and conditional fields are validated by this calculator’s own engine.
Pipe Friction Loss Calculator results
How to use the pipe friction loss calculator
This pipe friction loss calculator uses a dedicated engine, live visual and explanations specific to this problem. Review the assumptions before using the output for purchasing, design, grading, pricing or operational decisions.
Primary Darcy–Weisbach calculation
This pipe friction loss calculator converts the entered flow, inside diameter and length to SI units, calculates velocity and Reynolds number, and selects a friction factor for laminar, transitional or turbulent flow. Major loss follows the Darcy–Weisbach equation.
Roughness and fitting losses
Choose a material roughness preset or enter custom absolute roughness. Enter the sum of fitting K values for elbows, valves, entrances and other components. Minor head loss is reported separately and converted to an equivalent length of the selected pipe.
Pressure and pump demand
The calculator converts friction head to pressure loss using fluid density and adds entered static elevation to form a preliminary pump head. Pump power uses flow, density, gravity, total head and entered efficiency.
Hazen–Williams comparison and limits
A Hazen–Williams water result is shown only as a comparison. Darcy–Weisbach is the primary general-fluid method. Actual systems may require temperature-dependent properties, pipe aging, non-Newtonian methods, valve curves, parallel branches, transient surge and manufacturer data.
Pipe Friction Loss Calculator questions
What is the difference between major and minor loss?
Major loss comes from wall friction along straight pipe. Minor loss comes from fittings, valves, entrances, exits and other local disturbances.
Should I use inside or nominal diameter?
Use actual inside diameter. A small diameter change can significantly alter velocity and head loss.
What friction factor is reported?
The calculator uses 64/Re for laminar flow, a turbulent approximation based on Reynolds number and relative roughness, and interpolation in the transitional range.