How do you calculate pump horsepower for water treatment?

Hydraulic Horsepower (HHP) = (Flow in GPM × Pressure in PSI) / 1714. Brake Horsepower (BHP) = HHP / Pump Efficiency. For example, a pump delivering 50 GPM at 150 PSI with 70% efficiency requires: HHP = 50×150/1714 = 4.37 HP, BHP = 4.37/0.70 = 6.25 HP, so you would select a 7.5 HP motor (next standard size up).

What is the difference between hydraulic HP and brake HP?

Hydraulic horsepower (HHP) is the theoretical power needed to move water at a given flow and pressure, assuming 100% efficiency. Brake horsepower (BHP) is the actual shaft power required, accounting for pump inefficiencies like friction and hydraulic losses. BHP is always higher than HHP. The motor must deliver at least BHP to the pump shaft.

What are standard motor HP sizes for pumps?

Standard NEMA motor sizes in HP are: 0.5, 0.75, 1, 1.5, 2, 3, 5, 7.5, 10, 15, 20, 25, 30, 40, 50, 60, 75, 100, 125, 150, 200, 250, 300. Always select the next standard size above the calculated brake horsepower to ensure adequate power under all operating conditions.

Pump Power & Motor Sizing Calculator

Pump Power & Motor Sizing Calculator | ForeverPure

Pump Power & Motor Sizing Calculator

Calculate hydraulic horsepower, brake horsepower, required motor size, kW equivalent, and annual energy cost for water treatment pump applications.

Application Presets

RO Feed Pump SWRO High-Pressure Booster Pump Transfer Pump

Pump Parameters

Flow Rate

Total Dynamic Head / Discharge Pressure

Pump Efficiency

Typical: centrifugal 60–85% | positive displacement 80–95% | high-pressure RO 80–90%

Motor Efficiency

Premium efficiency motors: 92–96% | Standard: 88–92%

Power Calculation Results

Hydraulic HP (HHP)

Water horsepower

Brake HP (BHP)

Shaft power required

Motor HP Required

Next standard size up

Power (kW)

Electrical input power

Formulas Used

HHP = (Flow [GPM] × Pressure [PSI]) / 1714 BHP = HHP / Pump Efficiency Motor HP = BHP / Motor Efficiency (then round up to next standard size) kW = BHP × 0.7457 / Motor Efficiency

Annual Energy Cost

Electricity Cost

$ / kWh

Operating Hours

hrs / day

Annual Energy Cost (365 days)

Daily Energy Use

kWh / day

Monthly Energy Cost

Annual Energy Cost

Specific Energy

kWh per 1,000 gal

Recommended Pump Lines

All Pumps & Pressure Boosting
CAT Pumps — High-pressure positive displacement pumps
Danfoss Pumps — High-pressure RO & desalination pumps

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