Physics

Pump Horsepower Calculator

Find the hydraulic and brake horsepower of a pump.

Flow rate (GPM)

Head

Specific gravity

Pump efficiency (%)

Calculated Output

Hydraulic HP (hp) 1.263

Brake HP (hp) 1.804

Formula: HHP = Q·H·SG ÷ 3960

Step-by-Step Breakdown

1. Values used:

2. Flow rate = 100 GPM

3. Head = 50

4. Specific gravity = 1

5. Pump efficiency = 70 %

7. Hydraulic HP = 1.263hp

8. Brake HP = 1.804hp

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The math behind it

Hydraulic HP = Q·H·SG ÷ 3960 (Q in GPM, H in ft). Brake HP divides by pump efficiency.

100 GPM, 50 ft, water, 70% → 1.26 hydraulic HP, 1.8 brake HP.

Why is brake HP higher?

It includes losses, so the motor must supply more than the hydraulic power.