Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Required brake horsepower
1.73
Hydraulic horsepower
1.21
Motor draw (kW)
1.29
Daily energy cost
$0.88
Monthly energy cost
$26.34
Annual energy cost
$320
Psst — share this and help Rex grow
One click, a permanent link with your numbers baked in.
How to use this
- 1Enter flow rate (gal/min).
- 2Enter total dynamic head (ft).
- 3Enter pump efficiency (%).
- 4Enter run hours per day.
- 5Enter electricity rate ($/kWh).
- 6Read your required brake horsepower on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
Hydraulic horsepower is flow times head divided by 3,960. Divide by pump efficiency to size the motor you actually have to buy.
Worked example
Using the values the calculator loads with:
Inputs
- Flow rate: 60 gal/min
- Total dynamic head: 80 ft
- Pump efficiency: 70 %
- Run hours per day: 4
- Electricity rate: 0.17 $/kWh
Results
- Required brake horsepower: 1.73
- Hydraulic horsepower: 1.21
- Motor draw (kW): 1.29
- Daily energy cost: $0.88
- Monthly energy cost: $26.34
- Annual energy cost: $320
What each field means
Inputs
- Flow rate (gal/min)
- The flow rate used in the calculation, measured in gal/min. Starts at 60 gal/min so you have a working example on load.
- Total dynamic head (ft)
- The total dynamic head used in the calculation, measured in ft. Starts at 80 ft so you have a working example on load.
- Pump efficiency (%)
- The pump efficiency used in the calculation, measured in %. Starts at 70 % so you have a working example on load. Accepted range: 20–95 %.
- Run hours per day
- The run hours per day used in the calculation. Starts at 4 so you have a working example on load. Accepted range: 0–24.
- Electricity rate ($/kWh)
- The electricity rate used in the calculation, measured in $/kWh. Starts at 0.17 $/kWh so you have a working example on load.
Results
- Required brake horsepower
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Hydraulic horsepower
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Motor draw (kW)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Daily energy cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Monthly energy cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual energy cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the pump horsepower & energy cost calculator work?
Hydraulic horsepower is flow times head divided by 3,960. Divide by pump efficiency to size the motor you actually have to buy. The underlying maths is: HP = GPM × head (ft) ÷ 3,960 ÷ efficiency.
What do I need to enter?
5 values: flow rate, total dynamic head, pump efficiency, run hours per day, and electricity rate. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the required brake horsepower result mean?
It is returned as a decimal number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Pump Horsepower Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/pump-horsepower
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/pump-horsepower" target="_blank" rel="noopener">Pump Horsepower Calculator — RevenueLab</a> (2026).</p>
Source: [Pump Horsepower Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/pump-horsepower) (2026).