Sump/Transfer Pump Calculator

Hydraulic kW = 9.81 × flow(m³/s) × head(m); shaft kW = that ÷ wire-to-water efficiency (0.45–0.7 typical). 5 L/s up 30 m needs ~1.5 kW hydraulic, ~2.7 kW (3.5 HP) real. Oversizing 'to be safe' buys throttling losses and short-cycling — size to the duty point.

Wire-to-water (pump × motor): quality matched systems 0.55–0.70; old, oversized or throttled installations 0.30–0.45 — field audits of Indian agricultural pumps average a dismal ~0.35. If your measured numbers imply less than 0.45, the replacement usually pays back within a year.

Check the trio: friction head from undersized pipes (see the head-loss tools — often the silent half of total head), a worn impeller (efficiency decays invisibly), and oversizing (running far off the curve). The litres-per-rupee output here benchmarks your system against an honest one.

Static lift (vertical distance) + friction losses (pipes, fittings, filters) + any pressure requirement at the outlet (drip systems need 1.5–2.5 bar ≈ 15–25 m). Forgetting friction and outlet pressure is why 'calculated' pumps disappoint — measure or compute all three parts.