Specific Speed (n_s) Calculator

Specific speed is the index that decides whether you need a radial centrifugal, mixed-flow, or axial-flow pump. Enter the rotational speed, BEP flow, and head per stage; the calculator returns n_s in both metric and US conventions and maps it to the BBP product line.

Formula reference: N_s = n · Q^0.5 / H^0.75 (US) and n_s = n · Q^0.5 / H^0.75 (metric). Conversion factor 51.6 (51.6 · n_s = N_s). Per ANSI/HI 14.1, double-suction impeller flow is halved when computing specific speed. Hydraulic Institute reference bands: radial 10–35 (metric) / 500–1,800 (US); mixed flow 35–160 / 1,800–8,000; axial flow 160–400 / 8,000–20,000.