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HP to ft³/day Calculator

How to Convert HP to ft³/day

The HP to ft³/day Converter calculates the flow rate in cubic feet per day (ft³/day) 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 ft³/day (Cubic Feet per Day):

\( \text{ft³/day} = \text{GPM} \times 192.5 \)

Combined Formula:

\( \text{ft³/day} = \frac{\text{HP} \times 3960 \times \text{Efficiency} \times 192.5}{\text{Head (ft)}} \)

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.
  • \( \text{ft³/day} \): Cubic feet per day, a unit of volumetric flow rate.
  • \( 192.5 \): Conversion factor (1 gallon = 0.133680556 ft³, multiplied by 1440 minutes/day).

Enter the horsepower, efficiency, head value, and select the head unit to calculate the flow rate in GPM and ft³/day.

Using the HP to ft³/day Converter

This converter is designed for applications in fluid dynamics, pump design, and hydraulic engineering to convert horsepower to flow rate in ft³/day.

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 ft³/day.

Example: Convert 2 HP to ft³/day 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. ft³/day: \( 41.029373 \times 192.5 = 7898.154258 \, \text{ft³/day} \)
  5. Result: \( 2 \, \text{HP} = 7898.15 \, \text{ft³/day} \)

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 ft³/day with Efficiency = 0.85 and Head = 50 ft (or equivalent in other units):

HP Head GPM ft³/day
1 50 ft 67.32 12956.10
2 1524 cm 134.64 25912.20
5 15.24 m 336.60 64780.50
10 600 in 673.20 129561.00
20 50 ft 1346.40 259122.00

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 ft³/day conversions:

  • Q: What is the difference between GPM and ft³/day?
    A: GPM (gallons per minute) measures flow rate in gallons, while ft³/day (cubic feet per day) measures flow in cubic feet. 1 GPM ≈ 192.5 ft³/day (1 gallon = 0.133680556 ft³ × 1440 minutes/day).
  • 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 192.5 (derived from 0.133680556 ft³/gallon × 1440 minutes/day) and provides results rounded to 6 decimal places for GPM and 2 for ft³/day 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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