Industrial Calculators and Tools

Pump head and power calculator

Estimate friction and fitting head loss by Darcy-Weisbach, add static lift for total head, and work out pump shaft power.

Flow rate (L/s)Pipe internal diameter (mm)Pipe length (m)Static lift (m)Darcy friction factor fSum of fitting loss coefficients ΣKPump efficiency (%)

Total pump head10.63 m

Velocity 2.55 m/s · friction + fitting head 4.63 m · shaft power 0.80 kW (water, density 1000 kg/m³)

Sizing estimate only. Confirm the friction factor (Colebrook–White / Moody chart), fitting K values, NPSH, motor margin and duty specification with the pump maker before purchase — especially for fire, drainage or hazardous services.

Formula

Friction + fitting head hf = (f·L/D + ΣK) × v²/(2g). Total head H = static lift + hf. Shaft power P = ρ·g·Q·H/η.

Standard / source

Darcy-Weisbach head loss with the Colebrook-White friction factor (Moody chart) is the standard method for pipe friction; fitting K values come from the fitting or pump maker's data.

Worked example

Flow 5 L/s in a 50 mm ID pipe: velocity = 0.005 / (π × 0.05²/4) ≈ 2.55 m/s. With f = 0.02, L = 30 m and ΣK = 2: hf = (0.02 × 30/0.05 + 2) × 2.55²/(2 × 9.81) ≈ 4.63 m. With 6 m static lift, H ≈ 10.63 m and shaft power at 65% efficiency ≈ 1000 × 9.81 × 0.005 × 10.63 / 0.65 ≈ 0.80 kW.

Safety note

Sizing estimate only. Confirm NPSH, motor margin and the duty specification with the pump maker before purchase — especially for fire, drainage or hazardous services, where the duty specification governs.