Pump Horsepower
Use the Pump Horsepower for plumbing planning. Enter Flow rate (GPM) and Total head (ft) to get a clear result, formula explanation, and practical checks.
Pump Horsepower measurements
Enter your values, then calculate.
Result
How to calculate pump horsepower
This calculator finds pump horsepower required based on flow rate, total head, and pump efficiency — a standard sizing calculation for water pumps.
How the calculation works
Horsepower = (Flow rate × Total head) ÷ (3960 × Efficiency ÷ 100), where 3960 is a standard conversion constant for GPM and feet of head.
Example
100 GPM flow rate, 80 ft total head, 70% efficiency: (100×80)÷(3960×0.70) = 8,000÷2,772 ≈ 2.89 hp.
Frequently asked questions
How is Result calculated?
Result = [Flow rate] × [Total head] ÷ (3960 × ([Pump efficiency] ÷ 100)).
Is the Pump Horsepower free to use?
Yes — every calculator on Simple Calculator Tools is free, runs in your browser, and does not require an account.
Pump Horsepower
Horsepower = (Flow rate × Total head) ÷ (3960 × Efficiency ÷ 100), where 3960 is a standard conversion constant for GPM and feet of head.
Let's understand your pump horsepower result.
Calculate a result above and this guide will help you interpret it using this calculator's own formula and explanation.
Pro Tips for Pump Horsepower
- Total head includes both elevation change and friction losses through the piping system — don't use elevation change alone.
- Pump efficiency varies by pump type and operating point — use your specific pump's rated efficiency at your expected operating conditions, not just its peak efficiency rating.
Common Pump Horsepower Mistakes to Avoid
- Using elevation change alone as 'total head' without adding friction losses from pipe length, fittings, and valves, which understates the true head the pump must overcome.
When to Use This Calculator
This calculator finds pump horsepower required based on flow rate, total head, and pump efficiency — a standard sizing calculation for water pumps.