Head-losses Calculator

hf = f · (L/D) · (V²/2g)
f = Colebrook-White (turbulent) or 64/Re (laminar)
Re = ρ·V·D / μ

Pipe parameters

Pipe diameter D (m)

Pipe length L (m)

Roughness ε (m) → use Reference Tables to look up

Flow rate Q (m³/h)

Fluid properties

Density ρ (kg/m³)

Viscosity μ (Pa·s) → use Reference Tables to look up

Upstream head (m)

// Results

Velocity

—

m/s

Reynolds No.

—

dimensionless

Regime

—

Friction factor f

—

Darcy-Weisbach

Friction loss hf

—

m (head)

Upstream pressure head	—
Downstream pressure head	—
Pipe cross-section area	—
Relative roughness ε/D	—
Kinematic viscosity ν	—

hl = F · hf (full-flow friction loss)
F = Christiansen adjustment factor
F = (1/N) · Σ[(k/N)^m], m = 1.852

Pipe parameters

Pipe diameter D (m)

Total pipe length L (m)

Roughness ε (m)

Total flow rate Q (m³/h)

Outlet configuration

Number of outlets N

First outlet position

Fluid properties

Density ρ (kg/m³)

Viscosity μ (Pa·s)

Upstream head (m)

// Results

Inlet velocity

—

m/s

Reynolds No.

—

dimensionless

Christiansen F

—

adjustment factor

Friction factor f

—

Darcy-Weisbach

Single-pipe hf

—

m (no outlets)

Adjusted loss hl

—

m (with outlets)

Upstream pressure head	—
Downstream pressure head	—
Flow per outlet	—
Outlet spacing	—
Relative roughness ε/D	—
Friction reduction vs. single pipe	—

Click Use value on any row to populate roughness or viscosity into both calculator panels. Values are automatically converted to match the active unit system.

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Pipe roughness ε

Absolute roughness by material

Material	Condition	ε (m)

* Mid-range value applied when a range is given

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Water viscosity μ

Dynamic viscosity vs temperature

Temp (°C)	μ (Pa·s)	ρ (kg/m³)

* ρ and μ values applied to both calculator panels