Plumbing & Fluid

Pump TDH Calculator

Build a single-run pump head estimate from supply and discharge conditions. Keep static lift, required pressure, straight-pipe friction and fitting losses visible, then compare hydraulic and shaft power at your chosen flow.

Change any input to update the calculation. Unit changes preserve the physical quantity.

CALCULATION SETUP

Inputs

Reservoir boundaries neglect velocity; open jet adds the pipe outlet velocity head.

Example clean commercial steel roughness; replace with actual condition or manufacturer data.

Sum manufacturer loss coefficients at the modeled pipe velocity; do not mix equivalent length and K twice.

Example water near 20°C. Temperature and fluid composition can change this significantly.

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Calculated locally in your browser. No sign-up or input upload.

YOUR CALCULATION

Results

Required positive pump TDH

22.722 m74.549 ft

Signed system head balance

22.722 m74.549 ft

Static elevation head

10 m32.808 ft

Boundary pressure head

10.216 m33.516 ft

Straight-pipe friction head

2.507 m8.225 ft

Fitting / valve loss head

0 m0 ft

Boundary velocity head

0 m0 ft

Pipe mean velocity

1.019 m/s3.342 ft/s

Reynolds number

50,726.675

Darcy friction factor

0.0237

Hydraulic power

0.445 kW1,517.925 BTU/h

Estimated shaft power

0.636 kW2,168.465 BTU/h
Static 10 mTDH 22.722 m
Pump head between supply and discharge boundaries · schematic, not to scale

Calculation breakdown

TDH balance
Elevation + pressure + pipe friction + fitting losses + boundary velocity head
Boundary
Reservoir → reservoir; boundary velocities neglected

Assumptions & checks

One uniform pipe run and one design flow are modeled. A branched system, suction NPSH, cavitation, pump curve, transients and operating-point selection require separate analysis.

K-values and efficiency are user inputs, not certified component data. No installation or pump design approval is implied.

Formula

Steady incompressible Bernoulli balance. Darcy friction uses 64/Re for laminar flow, Colebrook iteration for turbulent flow and a stated interpolation for the uncertain transition region.

TDHsigned = Δz + Δp/(ρg) + (fL/D + ΣK)v²/(2g) + Δ(vboundary²)/(2g); Pwater = ρgQ max(0,TDHsigned); Pshaft = Pwater/η

Worked example

Using the default values shown in the calculator, the same formula gives the following result. This is a quick sanity check for the calculation, not a design recommendation.

Inputs

Design flow
2 L/s
Actual pipe inside diameter
50 mm
Total straight-pipe length
100 m
Supply boundary elevation
0 m
Discharge boundary elevation
10 m
Supply gauge pressure
0 kPa
Required discharge gauge pressure
100 kPa
Boundary velocity model
Reservoir → reservoir
Absolute pipe roughness
0.045 mm
Total fitting / valve K
0
Fluid density
998.2 kg/m³
Kinematic viscosity
1.004 cSt
Assumed pump hydraulic efficiency
70 %

Result

Required positive pump TDH
22.722 m
Signed system head balance
22.722 m
Static elevation head
10 m
Boundary pressure head
10.216 m
Straight-pipe friction head
2.507 m
Fitting / valve loss head
0 m
Boundary velocity head
0 m
Pipe mean velocity
1.019 m/s
Reynolds number
50,726.675
Darcy friction factor
0.0237
Hydraulic power
0.445 kW
Estimated shaft power
0.636 kW

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Technical references for this calculation

Reference lookupPipe Thread Reference

Frequently asked questions

Why are elevation and pressure separate?

They are distinct boundary energy terms. A high tank needs static lift; a pressurized outlet may also need pressure head. Equal pressure on both boundaries cancels.

Should I add outlet velocity head for a tank?

Usually not when comparing large reservoirs with negligible boundary velocities. Choose the open-jet mode only for a reservoir-to-open-pipe discharge represented by this single-bore model.

What does negative signed head mean?

The entered boundary heads may drive the requested flow without positive pump head in this model. The tool reports positive pump TDH as zero and retains the signed balance for review.

Reference data & method sources