Engineering Tools

Pipe Friction Loss Calculator

Calculate pipe friction loss, flow velocity and total dynamic head for water pumping systems.

Calculation Inputs

Suitable for borehole, irrigation, surface water and general water pumping applications.

Flow Rate

Pipe Material

Internal Pipe Diameter

Use actual internal diameter, not nominal DN size.

Total Pipe Length

Static Head / Elevation

Enter 0 for a level run.

Pipe Fittings

Enter how many of each fitting the run carries. Each count is multiplied by the K value printed beside it, and the sum is applied to the velocity head.

90° Elbows K = 0.90
45° Elbows K = 0.40
Branch Tees K = 1.80
Run Tees K = 0.60
Ball Valves K = 0.05
Gate Valves K = 0.15
Check Valves K = 2.00
Angle Valves K = 2.00

The three results that make up the total are shown below the two main figures. Change any input after calculating and the results are recalculated with it.

Calculation Results

Total Dynamic Head

— m

The static head plus every loss the flow meets. The pressure the outlet has to hold is not part of this figure.

Pressure Loss

— bar

Flow Velocity

— m/s

Straight Pipe Friction Loss — m
Fittings Loss — m
Total Pipe Loss — m

No safety margin is added to these figures.

How It Is Calculated

The formulas behind the results.

Three formulas give every figure in the results panel, and two short steps put them together. Nothing else is applied to them.

Straight pipe loss

Hazen-Williams formula

h_f = 10.67 × L × Q^1.852 / (C^1.852 × D^4.87)

h_f: Head loss, m
L: Pipe length, m
Q: Flow rate, m³/s
C: Hazen-Williams coefficient
D: Internal pipe diameter, m

Flow velocity

From the flow rate and the bore of the pipe

V = Q / A · A = πD² / 4

V: Flow velocity, m/s
Q: Flow rate, m³/s
A: Pipe cross-sectional area, m²
D: Internal pipe diameter, m

Fittings loss

From the sum of the K values of the fittings

h_m = ΣK × V² / 2g

h_m: Fittings loss, m
ΣK: Sum of the K values, each count × its K
V: Flow velocity, m/s
g: 9.80665 m/s²

Total dynamic head

TDH = Static Head + Straight Pipe Loss + Fittings Loss

Pressure loss

Pressure Loss (bar) = Total Pipe Loss (m) × 0.0980665

What this figure covers: the lift from the water level and the losses in the pipe and the fittings. It does not include the pressure the outlet has to hold. Where a sprinkler, a drip line, a pressure-compensating emitter or a tank inlet needs its own operating pressure, add that pressure to the total head: 1 bar is about 10.2 m, so a 2 bar requirement adds about 20 m to the figure above. A run that discharges freely needs nothing added.

Flow rate is entered in m³/h and converted to m³/s (Q = Flow Rate / 3600), and the internal diameter is entered in mm and converted to m (D = Internal Diameter / 1000). The Hazen-Williams coefficient used is the C printed beside the selected material, and the K values are the ones printed on the fitting fields above.

Pump Types

Which pump type fits the application?

The calculation above gives the total head the pump has to meet. The pump itself follows the water source, which is how the range is entered.

Groundwater

Wells & boreholes

Deep-well submersible pumps, for water drawn from a well or a borehole.

See the pumps

Surface Water

Rivers, lakes & canals

Surface pumps, for water taken from a river, a lake, a reservoir or a canal.

See the pumps

Storage & Distribution

Tanks & water networks

Multistage and centrifugal pumps, for transfer, boosting and distribution.

See the pumps

Wastewater

Sewage & drainage

Submersible sewage pumps, for wastewater and drainage duty.

See the pumps

The full solar water pump range is read by the water source it serves. Open the pump range

Calculation results are for preliminary system design reference. Actual pipe losses may vary depending on pipe condition, fittings, installation quality and operating conditions.