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HP to m³/s Calculator

How to Convert HP to m³/s

The HP to m³/s Converter calculates the flow rate in cubic meters per second (m³/s) from horsepower (HP), efficiency, and head using the following steps:

Step 1: Convert Head to Feet (if needed):

\( \text{Head (ft)} = \text{Head (cm)} \times 0.0328084 \)
\( \text{Head (ft)} = \text{Head (m)} \times 3.28084 \)
\( \text{Head (ft)} = \text{Head (in)} \times 0.0833333 \)
\( \text{Head (ft)} = \text{Head (ft)} \times 1 \)

Step 2: Calculate GPM (Gallons per Minute):

\( \text{GPM} = \frac{\text{HP} \times 3960 \times \text{Efficiency}}{\text{Head (ft)}} \)

Step 3: Convert GPM to m³/s (Cubic Meters per Second):

\( \text{m³/s} = \text{GPM} \times 0.000063090196 \)

Combined Formula:

\( \text{m³/s} = \frac{\text{HP} \times 3960 \times \text{Efficiency} \times 0.000063090196}{\text{Head (ft)}} \)

Where:

  • \( \text{HP} \): Horsepower, a unit of power.
  • \( \text{Efficiency} \): Pump efficiency as a decimal (e.g., 0.85 for 85%).
  • \( \text{Head} \): Total dynamic head in selected unit (cm, m, in, or ft), converted to feet.
  • \( \text{GPM} \): Gallons per minute, an intermediate flow rate unit.
  • \( \text{m³/s} \): Cubic meters per second, a metric unit of volumetric flow rate.
  • \( 0.000063090196 \): Conversion factor (1 US gallon = 3.785411784 liters ÷ 1000 ÷ 60 seconds).

Enter the horsepower, efficiency, head value, and select the head unit to calculate the flow rate in GPM and m³/s.

Using the HP to m³/s Converter

This converter is designed for applications in fluid dynamics, pump design, and hydraulic engineering to convert horsepower to flow rate in m³/s.

Input the horsepower (HP), efficiency (as a decimal), head value, and select the head unit (cm, m, in, or ft). The calculator will convert the head to feet and display the flow rate in both GPM and m³/s.

Example: Convert 2 HP to m³/s with 0.85 efficiency and 5000 cm head.


  1. Horsepower: \( 2 \, \text{HP} \), Efficiency: \( 0.85 \), Head: \( 5000 \, \text{cm} \)
  2. Head in feet: \( 5000 \times 0.0328084 = 164.042 \, \text{ft} \)
  3. GPM: \( \frac{2 \times 3960 \times 0.85}{164.042} = 41.029373 \, \text{GPM} \)
  4. m³/s: \( 41.029373 \times 0.000063090196 = 0.002588 \, \text{m³/s} \)
  5. Result: \( 2 \, \text{HP} = 0.002588 \, \text{m³/s} \)

Use this tool for accurate conversions in engineering and fluid flow calculations.

Common Conversion Table

The following table provides quick reference conversions for HP to m³/s with Efficiency = 0.85 and Head = 50 ft (or equivalent in other units):

HP Head GPM m³/s
1 50 ft 67.32 0.004246
2 1524 cm 134.64 0.008493
5 15.24 m 336.60 0.021232
10 600 in 673.20 0.042464
20 50 ft 1346.40 0.084928

Use this table for quick lookups or to verify calculator results. Note: Head values are equivalent to 50 ft (1524 cm, 15.24 m, 600 in).

Common FAQ

Below are frequently asked questions about HP to m³/s conversions:

  • Q: What is the difference between GPM and m³/s?
    A: GPM (gallons per minute) measures flow rate in US gallons, while m³/s (cubic meters per second) measures flow in cubic meters. 1 GPM = 0.000063090196 m³/s (1 US gallon = 3.785411784 liters ÷ 1000 ÷ 60 seconds).
  • Q: Why is efficiency needed in the calculation?
    A: Efficiency accounts for energy losses in pumps or systems, expressed as a decimal (e.g., 0.85 for 85% efficiency).
  • Q: What units can I use for head?
    A: You can input head in centimeters (cm), meters (m), inches (in), or feet (ft). The calculator converts all inputs to feet for computation.
  • Q: How accurate is this converter?
    A: The converter uses the precise factor 0.000063090196 (1 US gallon = 3.785411784 liters ÷ 1000 ÷ 60) and provides results rounded to 6 decimal places for both GPM and m³/s for accuracy.
  • Q: Can negative values be used?
    A: Negative HP or head values are not physically meaningful. Efficiency should be between 0 and 1. The calculator enforces positive head values.
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