Pump Horsepower & TDH Calculator
Size pump motors from flow and total dynamic head — water HP, brake HP, motor input HP, energy use and annual cost.
Formulas
TDH (ft) = static head + friction head + 2.31 × pressure (psi) + V²/(2g), g = 32.2 ft/s²
Water HP = Q (gpm) × TDH (ft) × SG ÷ 3960
Brake HP = WHP ÷ pump efficiency · Motor input HP = BHP ÷ motor efficiency
kW = HP × 0.7457 · annual kWh = kW × hrs/day × 365
TDH (ft) = static head + friction head + 2.31 × pressure (psi) + V²/(2g), g = 32.2 ft/s²
Water HP = Q (gpm) × TDH (ft) × SG ÷ 3960
Brake HP = WHP ÷ pump efficiency · Motor input HP = BHP ÷ motor efficiency
kW = HP × 0.7457 · annual kWh = kW × hrs/day × 365