Submersible Pump HP Calculator for Pool

Pump Horsepower Equation:

\[ HP = \frac{Q \times H \times SG}{3960 \times \eta} \]

Flow Rate (Q):

GPM

Head (H):

feet

Specific Gravity (SG):

(dimensionless)

Efficiency (η):

decimal (0-1)

Required Horsepower (HP):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Pump Horsepower Calculation?

The pump horsepower calculation determines the power required to move a specific volume of fluid against a given head pressure, accounting for the fluid's properties and pump efficiency. It's essential for selecting the right pump for pool applications.

2. How Does the Calculator Work?

The calculator uses the pump horsepower equation:

\[ HP = \frac{Q \times H \times SG}{3960 \times \eta} \]

Where:

\( Q \) — Flow rate in gallons per minute (GPM)
\( H \) — Total dynamic head in feet
\( SG \) — Specific gravity of the fluid (1.0 for water)
\( \eta \) — Pump efficiency as a decimal (typically 0.7-0.9)
3960 — Conversion factor to horsepower

Explanation: The equation calculates the theoretical power required to move the fluid, then divides by pump efficiency to account for energy losses.

3. Importance of Proper Pump Sizing

Details: Correct pump sizing ensures efficient operation, prevents energy waste, and extends equipment life. Oversized pumps can cause cavitation and increased wear, while undersized pumps won't meet performance requirements.

4. Using the Calculator

Tips:

For standard pool water, use SG = 1.0
Typical pump efficiency ranges from 70-90% (0.7-0.9)
Include all head losses (pipe friction, fittings, elevation) in total head
Always round up to the next available pump size

5. Frequently Asked Questions (FAQ)

Q1: What is total dynamic head?
A: The total resistance the pump must overcome, including static lift, pipe friction, and fitting losses.

Q2: How do I determine flow rate for my pool?
A: A common rule is to circulate the entire pool volume every 6-8 hours (pool volume in gallons ÷ desired turnover time in minutes = GPM).

Q3: What's a typical efficiency for pool pumps?
A: Standard pumps: 70-80%. High-efficiency pumps: 80-90%. Always check manufacturer specifications.

Q4: Should I add a safety factor?
A: It's common to add 10-20% to the calculated HP to account for system variations and future needs.

Q5: How does this differ for saltwater pools?
A: Saltwater has slightly higher SG (about 1.02), but the difference is usually negligible for pump sizing.