Fluid & Piping

Pipe Pressure Drop Calculator

Estimate Darcy-Weisbach friction loss, minor losses, static head and total head required for a pipe run.

“I need to run 50 metres of new 100NB pipe to a new tank. Will my existing pump have enough head?”

Core formulae

Pipe pressure drop reference

Average velocityv = Q / A

Reynolds numberRe = ρ v D / μ

Straight-pipe lossh_f = f (L/D) (v² / 2g)

Minor lossh_m = ΣK (v² / 2g)

Total headH_total = h_f + h_m + Δz

Darcy friction factor f is solved from the laminar or turbulent flow model used in the calculator.

Simple arrangement sketch

Pump to tank line

Choose the pipe size

Use DN/NB plus schedule when you know it. Enter actual ID for other pipe systems or measured pipe.

How do you know the pipe size?Nominal pipe sizePipe scheduleSchedule controls wall thickness, so DN alone is not enough to determine flow area.

Resolved internal diameter102.26 mmVerify the actual pipe standard, schedule, lining, scale and corrosion before relying on a final design result.

Flow, length and pipe condition

Start with common roughness presets, then override the value when better project information is available.

Flow rateFlow unitStraight pipe lengthmPipe roughness starting pointAbsolute roughnessmmEditable. Actual age, corrosion, deposits and lining condition can dominate this value.Minor-loss coefficient ΣKAdd valves, bends, entrances and fittings from your chosen project data source.Static elevation changemPositive when the discharge point is higher.Available pump headmOptional comparison at the required flow.

Choose the fluid

Water viscosity changes noticeably with temperature. A preset fills the values, but both remain editable.

Fluid presetFluid densitykg/m³Dynamic viscositymPa·sUse dynamic viscosity μ. 1 mPa·s = 1 cP.

Results

Estimated system requirement

Total head required11.17 m

Pipe internal diameter used102.26 mm

Pipe velocity3.38 m/s

Major friction loss5 m

Minor loss1.17 m

Dynamic pressure drop60.4 kPa

Darcy friction factor0.0176

Reynolds number344,553

Turbulent

Pump head margin18.83 m

The entered pump head exceeds the calculated requirement

Screening margin: 18.83 m. Confirm this against the actual pump curve at the required flow, not only the nameplate shut-off head.

Method

Darcy-Weisbach major loss plus ΣK minor losses and the entered static elevation. Turbulent friction factor uses the Haaland approximation; laminar flow uses 64/Re.

Job-file record

Save the calculation, not just the number.

Copy a permalink that reloads these inputs, or download a PDF record with inputs, visible results, assumptions, a sensitivity note, date and disclaimer.

Important boundary

A calculator can show the arithmetic. It cannot establish every requirement that applies.

Confirm the actual equipment, loading, materials, condition, jurisdiction, contractual requirements, standard edition and current project documentation before using the result for design, repair, testing or lifting decisions.

Ask an engineer about this calculation →

Pipe Pressure Drop Calculator

Pipe pressure drop reference

Pump to tank line

Choose the pipe size

Flow, length and pipe condition

Choose the fluid

Estimated system requirement

Save the calculation, not just the number.

A calculator can show the arithmetic. It cannot establish every requirement that applies.

Keep working the problem.

AS 4041 pipe wall & MAOP

Pipe flow velocity

Straight pipe friction loss