Hydraulic Horsepower Calculator

Calculator Inputs

Pressure

Enter pressure.

Pressure Unit

Flow

Enter flow.

Flow Unit

Duty Factor

Use 1.00 for steady load. Try 0.70 for average duty.

Sizing Margin (%)

Adds a peak allowance for conservative equipment sizing.

Efficiency Mode

Simple (overall)

Detailed (volumetric × mechanical)

Overall Efficiency (%)

Typical combined value for pump + motor + drive losses.

Volumetric Efficiency (%)

Leakage effects; lower values increase required input power.

Mechanical Efficiency (%)

Friction and mechanical losses in the system.

Tip: If you only know one number, use Simple mode. If you have both efficiencies, Detailed mode estimates overall automatically.

Reset

Formula Used

The calculator uses standard fluid power relationships. In imperial units: Hydraulic horsepower = (Pressure in psi × Flow in gpm) ÷ 1714.

In metric units: Power (kW) = (Pressure in bar × Flow in L/min) ÷ 600.

Estimated input power includes efficiency and duty: Input power = Theoretical power × Duty ÷ (Efficiency/100). Peak sizing adds the selected margin percentage.

How to Use This Calculator

Enter the operating pressure and choose the correct pressure unit.
Enter the flow rate and select its unit.
Pick an efficiency mode: overall, or volumetric × mechanical.
Set duty factor for average loading and margin for conservative sizing.
Press Submit to see results above, then download CSV or PDF.

Example Data Table

#	Pressure	Flow	Efficiency	Duty	Margin	Theoretical (hp)	Input (hp)
1	2500 psi	12 gpm	85%	1.00	15%	17.51	20.60
2	180 bar	45 L/min	88%	0.80	10%	14.40	16.36
3	22 MPa	2.0 m³/h	90%	1.00	0%	10.93	12.14

Values are illustrative. Your results update after Submit.

FAQs

1) What is hydraulic horsepower?

It is the power carried by the fluid, based on pressure and flow. It estimates how much useful power the hydraulic circuit can deliver before losses.

2) Why does efficiency change the input horsepower?

Losses from leakage, friction, and heat mean the motor must supply more power than the fluid delivers. Dividing by efficiency estimates required input power.

3) Should I use simple or detailed efficiency mode?

Use simple mode when you have one overall efficiency estimate. Use detailed mode if you know volumetric and mechanical efficiencies and want overall calculated automatically.

4) What duty factor should I choose?

Use 1.00 for steady continuous load. Choose less than 1.00 for average operating load, such as intermittent cycles where pressure and flow are not constant.

5) What margin percentage is reasonable?

Many designers start with 10–20% to cover transients and uncertainty. For highly variable loads, consider a higher margin, but verify against component limits.

6) Does temperature or oil viscosity affect this calculation?

The basic power formula does not, but real efficiency does. Higher temperature and lower viscosity can increase leakage, reducing volumetric efficiency and raising required input power.

7) Why are there both hp and kW outputs?

They are the same power expressed in different units. The calculator computes both so you can match motor ratings, datasheets, and regional engineering practices.

8) Can I download results for reports?

Yes. After you run a calculation, use the CSV or PDF buttons in the results box. Downloads include inputs, assumptions, and calculated power values.