Darcy Pipe Head and Pressure Loss Calculator
Estimate straight circular-pipe and entered minor losses with an explicit Darcy friction factor convention.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Convert all dimensions to SI, calculate mean velocity and Reynolds number, then use laminar 64/Re or solve Colebrook for turbulent flow. Add entered minor losses.
Head=(fL/D+ΣK)v²/(2g); pressure loss=ρg×head; turbulent 1/√f=−2log10(ε/(3.7D)+2.51/(Re√f))
Worked example
A 0.01 m pipe with 1 m length, mean speed 0.1 m/s, density 1000 kg/m³ and viscosity 0.001 Pa·s has Re=1000 and Darcy f=0.064. With no minor losses the pressure loss is 32 Pa.
Assumptions and input details
Fully developed, steady incompressible single-phase flow in a rigid circular pipe. Darcy factor is four times the Fanning factor. Automatic mode rejects 2300≤Re<4000 rather than choosing a transition factor. Roughness ≤10% diameter; Re≤10^12. No elevation, entrance development, compressibility, pump curve or allowable-pressure assessment.
References: NASA KSC thermal/fluid engineering formulas
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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