Pumps - Specific Speed Calculator

Calculate the specific speed of a pump using the formula Ns = n × q^0.5 / h^0.75. Specific speed identifies the geometric similarity of pumps and is independent of pump size. Supports multiple unit systems including US gpm, British gpm, m³/h, and liters/min.

Calculator

Inputs

Pump Shaft Speed (rpm)

Flow Rate (gpm)

Head Rise (ft)

Unit System

Results

Specific Speed (Ns)-- Ns

Pump Type Classification--

From	To	Conversion Factor
Ns (m³/h, m)	Ns (US gpm, ft)	0.861
Ns (m³/h, m)	Ns (British gpm, ft)	0.787
1 US gpm	m³/h	0.2271
1 British gpm	m³/h	0.2728
1 ft	m	0.3048

Pump Design	Specific Speed Range	Characteristics
Radial Flow	500 - 4,000	Centrifugal impeller with radial vanes; double and single suction
Mixed Flow	2,000 - 8,000	Mixed impeller single suction pumps
Axial Flow	7,000 - 20,000	Propellers and axial fans

Turbine Type	Specific Speed Range
Francis Turbine	70 - 500
Kaplan / Propeller Turbine	100 - 350
Pelton / Turgo / Cross-flow Turbine	10 - 80